Hi,
difficult, but not impossible.
Just take a "cheap" tank kit with rubber chains.
A IR remote system or a small rc reciver (a tank scaled 1:87 is large enough).
2 speedcontroler for the chaindrive
1 speedcontroler for the "dradger" in front
1 speedcontroler for the bridge
the bridge may work by using a gear and a rope.
I am looking forward to see your first pictures!!!
best regards
Thorsten
www.mikromodell.de
p.s. working guns will also possible by using gunpowder in a pipe (injection needle) and a brasswire as the bullet. A resistorwire is fine to initialise the shoot ;-)