As I was told by a judge at a model contest in San Antonio, a diorama depicts movement without actually moving the subject around (in or on the base).
1: a scenic representation in which a partly translucent painting is seen from a distance through an opening
2 a: a scenic representation in which sculptured figures and lifelike details are displayed usually in miniature so as to blend indistinguishably with a realistic painted background
b: a life-size exhibit (as of a wildlife specimen or scene) with realistic natural surroundings and a painted background
I say put him where you feel he will bring the best results as graeylin said. Good luck bud.
OH-58C Crew Chief 89' to 92' C Troop 1-7 Cavalry...Desert Storm Vet