This Rollaway Observatory Is Keeping Me Up At Night

I keep looking for alternative ways to have a water proof structure that will enclose a 26" square by 4' x 7' telescope that I can roll away to get a clear sky with minimal horizon obstruction and still allow the rolling telescope ladder to get close.

I played with the idea of four fiberglass walls sitting on casters in aluminum channels set into the concrete.  Take the top off and pick up and move side walls.  I can see spending a pile of money to have leaks.

Walls fold down but the rolling ladder goes over and damages the walls.

The only thing that seems to make sense is a building 4' tall inside x 2.5 ' deep and 7' long with doors that open wide enough on at least side to roll the structure away from the telescope.   It need not even be rolling in rails.  It could just roll on the concrete pad.  The height is to reduce sight line blockage for our neighbors; that is below the height of our sage.  Rolled away it is still below that sight line.

Search for floorless sheds.  They seem to be either 6' wide or 6' high or 2' deep.

I would prefer resin.  It goes with the architecture better and would likely stand up to being rolled better.