Sounds great, you won't have any problems with the MDF sagging, if you are just planning to route the MDF or lay plastic track down. It will be a severely heavy peice of kit, hope you are fit!
I've used a ping pong table for the same effect which is effectively about 25% lighter gauge all round - thinner board, lighter frame, folds in two not one - really no problem carrying both HO and Scaley layouts. I wouldn't put masses of mountain-type scenery on it though.
One advantage of the latter is that the surface is sealed 100% top, bottom, sides to protect from damp etc. Might be a good idea to paint your MDF before assembly.
Good luck, keep us posted
I've used a ping pong table for the same effect which is effectively about 25% lighter gauge all round - thinner board, lighter frame, folds in two not one - really no problem carrying both HO and Scaley layouts. I wouldn't put masses of mountain-type scenery on it though.
One advantage of the latter is that the surface is sealed 100% top, bottom, sides to protect from damp etc. Might be a good idea to paint your MDF before assembly.
Good luck, keep us posted