I've used the 8x10 tubes successfully with Paterson 12x16 plastic trays. You don't need gallons and gallons of solution. All you have to do is plunge the tubes in and quickly spin them a few times to make sure the emulsion is quickly covered with stop bath. You don't need to fill the trays to much depth for that to work.
Re your last posting, I bought my 8x10 BTZS tubes (all 2 of them <g>) about 6 years ago, and compared to what you describe, they were rather more elaborately and smoothly finished out of machined and glued parts. But bear in mind that there have been long intervals when BTZS tubes larger than 4x5 were entirely unavailable, because they couldn't find anyone to manufacture them at a price anywhere within reason. So the realistic standard to judge the current ones is against the likelihood that there'd be no product at all now if more expensive manufacturing techniques were required.
All that said, I quickly gave up on the tubes, and have kept mine around only for emergencies. I'm much happier with my Jobo + Expert drums, which produces cleaner and more consistent results with much less hassle. For those who are fortunate to be able to afford one, I'd recommend a Jobo over the BTZS tubes any time...