One can buy an R/C American Halftrack with a quad .50 in the back. The gun turns, elevates and shoots (noise only). It is driven by the tracks but the front wheels do work with it.
Not a huge price, last I knew about $175 ... and yes, I DID own one. Very unhappy about both how it handled and the speed so I sold it.
I have kicked around the idea of buying another one and going at it to see if I could "adjust" the speed one way or another. Since I only collect German WW2 R/C it would get treated/detailed as a captured piece of equipment.
After spending most of my life riding bikes I can take one look at those single track machines and know I wouldn't care for either one.
I finished (for now) the trailer for the tank hauler, I will start on the HT conversion of adding a 3 ton?crane on the rear deck tomorrow.