I am looking for peak cooling at lower than racing rpms. The fan and water pump being belt driven, perform best at higher rpm. Electric out performs belt drive in the lower rpm range.
Um no.
A belt driven clutch fan will outperform electric at lower rpm in almost every case.
Your typical thermostatic clutch fan turns at 30% when free and around 80% when engaged.
It takes very little force to turn the fan when free. I recommend a 5 blade(sbc car) and if you can fit it a 7 blade(bbc truck). You will feel and depending on the shroud hear when a 7 blade comes on.
By comparasion a electric will keep your engine cool and there are some powerful motors out. But more powerful motor are going to draw more amps. Your trading the clutch fan using engine power for the alternatior using engine power.
At low rpm that clutch fan is going to perform great as it is thermostatic (temperature) engauged not rpm based.
If you have a electric motor(s) that can move as much air as a 7 blade then at low rpm they are going to tax the electrical at idle for extended periods(like crawing offroad). The reason is s10/s12 63/96ish are only rated at those rpm above 3000rpm. They do horrible at idle or low rpm speeds. It is just the curves. The CS series like a cs130 which bolts in place of most s10/12 have a much better low rpm curve.
Tons of threads and step by step writeups on swapping from a s10/12 to a cs130 alternatior that will allow allow heavy amp electric fans to run without issue.
Ok onto your clearance issue.
You can straddle 2 fans easily.
Here is 3 fans in a old(very low cost) setup in my basement.
I have even ran 4 fans.
I always to run a dual or perferably tripple pass radiatior or at the very least run a all aluminum radiatior.
I dont have a issue cutting up the core support to set the radiatior under the core support to gain clearence to run a clutch fan. Of course this means your running a closed radiatior with a remote fill in the upper line or such.
But you can generally straddle the fans in a way where you wont need to move the radiatior forward.
Once the radiatior and fans are covered I go a step further and run 1.5" copper pipe instead of hose or AN-16 line(1") The copper pipe sheds heat(be mindful of where you put your arms) and can not collapse. Of course this is only recommended for straights. Copper also looks nice when polished.
Before you think about running a 180 or less thermostat or none at all. I will tell you from experence you want a 195F thermostat. Very short thermodynamic lesson here. Basically, the hotter you keep the cylinders the less thermal losses you will have when that compressed gas/air mixture explodes. This means keeping those cylinders hotter(within reason) the more power your going to make.
You want cold (dense) air going into those cylinders for more oxygen. But the actual water surrounding those cylinders you want hot to lessen thermal losses.
A 195F thermostat will keep that engine around 200 to 210 for hours driving at 1000rpm offroad or hours running 4000rpm down the highway. Speaking from experence here. I have had 4.5x and even 5.xx gearing running down the highway without issue for hours. Basically stopping because of the single didgit mileage to refuel. But I am telling you what works from experence.
Now, onto the actual post about remote cooliers.
First off just like you dont want your coolant to cold you also dont want your transmission/engine oil to cold. It has a range it likes to run at. In most cases simply running a heat sink is enough to see a noticable drop in engine/transmission oil temps. The simple fact your increasing capacity by running lines to a remote heatsink will keep things cool. Once again you can use copper(nicopp not freezer line) to have the line shed heat as the oil passes through it. If course you still need to use rubber for the flexable areas. But using nicopp will avoid a oil line rubbing the frame between the clamps. Use clamps to secure any lines to save you headaches.
Generally a remote oil filter(plate setup) will give you enough cooling capacity. Transmission you can also use a remote filter on. These filters act as a heatsink while being a filter(additional filter with auto transmission) and can be placed in a easy to reach area. If the engine bay is tight in a s10 then positioning the filters under the bed can make for easy replacment. But generally the remote filters will fit in that area by the blower motor, against the firewall once the AC is deleted or by the headlight the battery is not next to.
Notice I did not mention electric fans with the remote filters. Because your adding capacity, and running lines that are sheding heat you will find those fans won't be needed or if on all the time will over cool the oil placing cold oil back into the hot engine.
Well on the topic of cooling we should talk about diff covers. It is often a area overlooked. But most covers are just a horrible design that causes aeration in the oil or prevents the oil from running over the top of the ring lubricating the pinion. Most stamped factory covers do a great job at lubrication and not that bad of a job at cooling.
When looking at aluminum cover you want a cover mimicking the inside of that factory stamped cover. Anything that has webbing or ribs on the inside where the factory cast cover is smooth(around the ring gear) is almost guaranteed to cause aeration and a loss of pinion lubrication.
This post is long. But only touches on the actual books written on the topic of cooling. Its one of those areas you can get advice on what to do. But every ride is diffrent and you need to see what works best of your ride.
