Tricycle gear or tail-sitter?
The only time I've done this so far was for a 1/72 Hurricane mounted on a wood base: I drilled holes in the base of the tyres and the wood and epoxied a 5mm piece of wire into each one to fix the plane in place. I also added a tiny dab of CA to the tail wheel.
In the event, the wheels were probably more secure on the base than the undercarriage was to the rest of the plane
Shipping it in diorama will be tough, all the forces will act on those fixing points and if you have fragile aerials etc you can't pack it out. Maybe you could separate and wrap the components for a small amount of easy assembly at the other end?