Probably the best idea when it comes to exhibition is make something small and simple!
Code 75 or code 100? Code 100 is more durable and more universal to what one can run on it, but if one is modelling the steam era, code 75 is more realistic. (As axle tonnages got heavier, heavier duty rails were used and some areas like Port Talbot heading east, had such deep rails that early Triang track would be passable to represent the prototype height!
Some modellers wanted to replicate these modern deep rail sections by using code 100, and then use code 75 in sidings to represent older lower profile rail. (Common to re-use worn main running line rails in sidings to give them an extra lease of life).
Anyway. Part of the issue for an exhibition layout is making a sturdy reliable layout when erected, but on lightweight boards that are small a nd easy to handle and transport. Also consider how far ones arms can reach when carrying boards!
Just a few things to think about... And also the need to carry tools and a few spares including power leads...