RE: 1/4 Dune Buggy in the works
For the section from the engine to the first shaft, just set up the engine with slotted mounts, and adjust the tension with that.
A simple tensioner on the rear chain should work ok.
You can pivot the rear suspension from the second sprocket shaft, using a second set of bearings.
Since this shaft will be spinning with the smaller sprockets, your chain will hold it's tension, through the range of rear suspension movement.