If you get a chance to look closely at the Tamiya kits, you'll see a lot of thought and engineering went into it. The suspensions on both the Tiger and the M4 behave realistically.
It would be a little more involved than say motorizing a Kubel, not to mention trying to create Panther tracks that would function.
I'm sure it can be done, with a huge effort and probable expense. Unless you are really experienced with RC, I'd try Tamiyas first, at least you would know what you're up against.
Years ago I used to build motorized eye systems for puppets and there are a lot of companies from who you could get any gear or part you want. Keep in mind Tamiya's Multi function units are top notch: power requirements and ratios, et al, have already been worked out.
You can always build a Tamiya and then figure a way to build a Panther with the units afterwards.