Boy oh boy was that quick, Thank You.
The weight shouldn't be much of an issue at all. We use bases just like these at work for under our tool boxes (and I've got about the same weight on my frame at work as what I figure the welders should weigh. I also like the idea of having less of a "footprint" by having both together rather two separate carts. But I see what you mean about the heft.
If I could weld a lot better, I'd build that first one. I think (out of the three so far), I'll shoot for making a 4 supporting leg unit similiar to the last one shown. Nice straight cuts of 1" square tubing (I really need to get my Sawz-all back from my Father-in-law) and a couple uprights of 1" angle shouldn't be too tough. Thanks again.
In a while, Chet.