I built my own trailer and have it set up so there is probably less than 30 lbs on the hitch (Prindle 18). When I had my H16 on the trailer, it sat farther forward and I had around 80 lbs up front. I can't tell the difference with towing on either setup. I just sold a different Hobie 16 that had well over 100 lbs on the hitch and it towed great also. It sounds like the consensus is that as long as you have a strong framework, the tongue weight isn't real critical on a cat trailer.
Fort Loramie, Ohio