I don't have parabolic springs but also have been toying with the idea of getting them. I do tow trailers of all kinds though with other vehicles and hitch/pin weight is very important, for a tag/bumper pull the hitch weight should be minimum 10% and up to 15% of the gross trailer weight. 120lbs would give a trailer and boat at 1200lbs total, any heavier and you don't have enough hitch weight. I can almost guarantee that if you tow there will be times you will hook something much heavier to the vehicle, I often move a small dump trailer 7-8000lbs loaded so my hitch weight is 1050lbs to 1200lbs, my 88 Landrover handles this no problem on the front or the rear. I tried this same trailer on the front of a 2006 jeep TJ with coil springs and it buried it. I'm trying to say if you tow at all don't stick some weak springs under it.
1971 series 2a 88, series 3 trans, Fairey OD, owned since 1978.