Only experience I have had on trike was some couple years ago when fellow bought one in lower end of South Carolina and not having a license asked me to go with him to ride it back home in WV. Well, away we go and sure enough a well equipped Gold Wing Trike ready to go. Interstate I77 all the way and as you mentioned, the partings/cracks in the road surface gave a little thump all the way up the road. Not severe, but after a while become annoying and tiring. Trucks gave some problems with "prop wash, dirty air" as well. The real problems showed up when we got back to WV with all the curves and switchbacks in the hills and mountains. This trike supposedly had the "easy steer" feature but I would have not wanted to try one without that for it was a real effort to make the turns. Have heard it said that trikes require "strong upper body strength..." and for this trike that was definitely true. Not ridden a Harley trike so the above may well not apply
and my local HD dealer seems to sell quite a few of them. Friend of mine does have a Softail converted to trike by independent, but for whatever reason the local HD dealer will not provide any level of service for that bike, not even an oil change. Something to check out in your location.