Hi Tony,
I used a design similar to that Stewart recommended. My roll-off observatory is 8’x10’. Due to rules stipulated by a higher power that you met at the BAA meeting, I had to split the roof into two halves each moving off in opposite directions. I purchases (2) 20’ pieces of angle iron. I was able to arrange free delivery as I was nearby to where they were making another delivery. Of course a bicycle could be a funny option depending on how far you would have to go:) I went with (8) 4” cast iron v-groove wheels with ball bearings. I cleaned up the angle iron and applied two coats of a Derusto brand paint. It is wearing off a bit but no problem so far after 3 years. I might reapply at some point with a brush. The wheels are rated at 800 pounds each. One wheel has a bit of rust but cosmetic only. I put a wood block at each track end as a stopper. I used some stainless steel cap screws every couple of feet to hold the rails in place on treated 4”x4” wood support beams, which on the outrigger ends are supported by treated 4”x4” treated posts set on concrete blocks with adjustable steel screw brackets. Of course as you know I live in the desert and you might encounter a wee bit more moisture. Each roof section rolls very easily.
Cheers!
Woody