With the multi-profiled tubing constructed in such a way as to purposely place your weight over the front to get the most from the long fork, there’s no getting away from the severely limited suspension. The Marzocchi MZ Comp’s internals cannot cope with any undulation. With no real damping, they recoil from even tiny bump far too fast.
With a compliant rear end, you could ride your way around the problem, but the Marin’s quite stiff out back meaning you get battered from both ends simultaneously. With geometry fit for purpose, it’s the fork preventing the bike being ridden how it needs to be.