How are you going to align the enlarger and easel (what kind of easel?) to make 40" prints? I made 16x20s from my 4x5s on my Omega D2 and it was a challenge. I do have a Versalab laser enlargement alignment tool and it wasn't cheap.
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How do you process 40" paper? In Maxwell photo mural tanks?
How about that, you live and you learn. I'd never seen a laser system. I think there was an optical system available at one time.
I have a bubble level I put in the enlarging head and adjust that way. It's not accurate to one wavelength but for real world applications it's perfectly good. I've been printing since we'll before lasers and this method worked fine.
I'd suggest remounting your enlarger on the baseboard so you can print vertically on the floor. Flipping the enlarger horizontal makes it very difficult to get the negative parallel to your paper. Vertically you can use tape on the edge of your paper or metal rods to hold the paper flat. Of you just lay the paper on the floor without securing it there's a good chance it'll curl. I've used a flat steel sheet like sheet metal and use magnets to hold the edges down. This is how I did it with horizontal projection.
I've run huge prints different ways. I've used large custom trays, huge deep tanks that hold several hundred gallons for large quantities of very large mural size prints and used a hoist to hold the paper racks. I've also made troughs out of plastic wallpaper troughs. I cut them apart and glued two together. This is awkward but it can be done. You might want to create something to support the sides of the troughs. They flex a lot
I also had a large drum someone fabricated on a home built motor base. I used it to run 60" color prints I was making from 8x10 negs.
Last, focusing is going to be difficult unless you have arms 8 feet long. Getting your head close to the focusing magnifier to see well and reaching the focus knob is a challenge. Many commercial enlargers used for large prints use servos on the focus and a remote so you can use a grain magnifier and still run focus.
You have some major challenges ahead. Is suggest trying some prints you can do on your baseboard first then get that worked out then move to larger. Printing gets much more difficult as you move up in size and much more expensive.
One more suggestion, I'm a huge fan of diffusion enlarging heads. They produce a smoother tonality, reduce the effects of dust and scratches and cold light heads like the zone VI and Aristo are cool and dnt cause neg buckling as badly. Some people feel they reduce sharpness but what they're seeing is the more subtle tones not a loss of sharpness. Prints from Diffusion heads are closer to what a contact print looks like.
Consistency is very important. Set a time like 2 min for RC and 3 for fiber paper development. Use something like Formulary TF 4 or 5 to fix. Fix times are shorter and wash times much shorter as well.
When you do a test strips, dry it in your microwave before evaluating to allow for drydown. Mistakes get expensive at that size.