you know what would be cool - and I think you could do it - instead of a war elephant have a War Rhino. Probably just some tweaking of the model. The size issue probably can be dealt with by enlarging the rider then reducing the unit scale so it fits to a large rhino. I think it would be a real cool flavor unit.
looks like strategyonly's mod has a rhino unit. you could do an easy swap
http://forums.civfanatics.com/showthread.php?t=181026&page=72
Looks good .