I dont understand why this is so complicated. An HT hull weighs like 75 pds? An I20 hull weighs like 125pds or thereabouts. When you fly a hull on the HT the shroud (which is attached to the mast) PICKS UP 75 pds out of the water and into the air. When you fly a hull on the I20 the shroud (which is attached to the mast) PICKS UP 125 pds of hull into the air (where it is not bouyant).

The difference between flying a hull and strapped to a dock is not a useful analogy unless you managed to fly a hull on the dock, which breaks either mast. Just dont fly a hull on the I20 and you'll be fine, but what fun would that be...