Chains, you can typically do with some kind of delrin runner or wheel that is adjustable and easy to access for spot checks and tensions between matches. you can also use a screw tensioning system where you draw back or push froward a block that either holds you wheel or sprocket.
Belts are basically the same and require good tensioning practices to continue to work properly, if not they are liable to break. we on 48 have used basically the same method ever since '06 on our treads and have only broken a few pairs since. it involves putting a screw tensioner into the system, but instead of moving one of your delrin wheels or an idler sprocket you are moving a splined toothed pulley.
I don't have the models or any pictures on my computer but I know of a few people who, if you ask nicely will help you out. one of them is
Mike Mellott, he was the head designer on our past couple of models for treads and we be the one to tell you how to use some form of screw tensioning system, the other two I don't know personally but probably know allot more than I do about drive train design and they would be,
Craig Hickman and
Madison Krass. look up some of they're work, I know one of them has a 6-wheel drive with a build in tensioner. remember they are probably busy with schooling and they're teams so do searches and some research before asking for explanations. most of the material can be found on CD.
I will try to find some of my old material and post it also.