couple of items to check.
Hello Bruce, Mounts are a good place to start. I’m not sure what engine you have but if the mounts current are soft a stiffer or shear loaded mount may help a great deal. Mounts are a consumable item, which may have a life span of a few years to ten-ish years. One thing pops to mind that there is no vibration astern. When system is going in reverse the prop is trying now to pull the engine out the back end of the boat. When in forward the shaft is being put under extreme compression. Looking at your location in MI, my guess is that the vessel is out of the water at this time? I would have the propeller shaft removed and sent to a prop shop to see if the shaft is bent slightly. The fact that the vibration is forward load and not astern load helps me think that the propeller is running pretty true. If the shaft comes out also have a fit a face of the coupling and have your prop checked for trueness. Good luck hope it helps. Kevin
