If you're handy enough, you can get a dual motor ESC and hook up to a DasMikro TBS for light and sound. You can even do flash. All the guys who convert their wiesels/renault FT use that to save space.

The trickiest bit is slowing turret rotation if you use a 360 servo connected directly to the Rx. I packed mine with grease to slow it. Some use gears connected to the servo. Some convert motors, etc.

If you have more space, IIRC open panzer works with Arduinos. From their website, seems like Torro sells a open panzer board too.