The issue I have found is tuning the suspension with the load you are running with. If you setup the boat tail with no extra cargo (static weight/mass), then tuning yer shocks will be a whole lot easier than loading it up. Through my trials, you will need some sort of weight and dampening to keep the back end from popping up and down due to the bumps in the road.
The smaller shocks don't have a large amount of an oil reservoir and will fade quicker due to the amount of air bubbles that will build up in the shock oil compared to a bigger oil reserve shock.