Haven't got time to comment on everything you've said.
Some tips:
Rails come in two pieces.
You can mount one piece to the drive and one to the rack.
When you have the rails in two pieces, the rack side rails
can be screwed in place with much less stuff in the way
than if the drive was there, so please do that.
Extend the rack rail and dock the drive rail to it.
Once you get one side docked, you can let it support *some*
weight, like half a drive weight, so you can move from gross
lifting to fine positioning at that later point.
Some rails are extendable.
You can loosen a screw and pull them out a little longer.
I've used nuts and bolts. Not much problem, I added locking
washers to them because these are machines that vibrate.
I've used piles of things to lift Eagles.
A table with a PC on it gave the right height and *important*
wasn't too rickety.
If the height wasn't exactly right it was alot easier lifting 1
inch than holding it up at four feet.
Eagles require friends when lifted.
John A.