I do a lot of woodworking and I use a lot of auto clear on my (unstained) mahogany and curly maple it looks great and all I do is bring it to the shop and clear them with left over clear.
One thing I found is that auto clear will scratch fairly easy ,my mahogany coffee table top is a good example of that ...in a truck bed that will get used the high gloss wont last long.
hardwood floor finishes do have a UV protection ,thats why they dont change color by all the windows,like auto clears they come in many qualities...Just like finishing cars use a stain and clear that are part of a system,that stuff is made for abuse.
the only other thing I can think of that I've used and is really tough is called "Varathane" liquid plastic,made by "Flecto" its an exterior ,marine clear.
When refinishing floor boards ,using a planer will make the job a lot easier,just run both sides through it and its like brand new wood,15 minutes and they're done ,No sanding...
something else that will help make the floors last is installing the boards with the cups up,so the stainless strips hold down the edges,and they dont crown in the middle,it makes a big difference down the road.
wood wants to move so make all your holes oval and just snug the bolts up so the wood can move.
Oak is NOT a good outdoor wood so seal it up good ...