So, I recently and finally pulled the trigger, and the Trinity cart (Phishy4's recommendation) from Costco online just arrived (they didn't have squat for in-store selection btw). As my tiny little thank you for all of the suggestions and advice, I'd like to give you all a couple of dark, crappy, blurry, and simply horrible before/after photos.
You can put it together without the directions, really super simple, just plug the tubes in, though I noted that they said to put both locking casters on the right side (totally arbitrary as far as I could tell; maybe it was only important that both were on the same side, whether left or right). I went with the left because by the time I realized which side was right, I had already worked the caster in a bit with my hands.
The only thing that stopped me from building the thing in 1 minute flat was getting the casters all the way in. At first I didn't want to hammer them in, out of fear of damaging a caster, but I was even more fearful to screw up the plastic hole by torquing sideways on accident with my hands when I gave that a little go. Then I grabbed my c-clamp to see if it might work, nope, then a pipe clamp, no go either. Rubber mallet would be too big, so I simply hammered them in after all, and voila.
Anyway, I just wanted to update you guys, and show that I do listen to and follow the advice given here, cheers. :xyxthumbs
Well shoot, I am failing to attach the couple of photos (a fatal error or something here). Oh well, I tried, and they were bad photos anyway.
Only going by the picture on a monitor, the Rubbermaid at more than 3x the cost does indeed look nicer and perhaps is more sturdily built, but I think this Trinity, while a tad more than I was hoping to spend, was exactly what I was looking for, functionally, and without the need to turn it into Frankenstein. I can foresee it helping out with completely different tasks unrelated to cars in the future as well. I'll grab a google photo so you can see which one the Trinity is. I think it was $75 or so, OTD.