1. are the damper shafts visible? if so, put a tywrap snug around the shaft right against the damper body, go drive, then see if the tywrap is now hard up against the top stop.
1b. if no access to damper shaft, look for a way to lightly attach something to the fixed chassis that will get knocked off by some moving part of the suspension near full travel; will need to be creative, but can be done.
2. squirt a good amount of baby powder or equivalent on the underside of the fenders, then drive, see if the tire rubs it off.