I have towed 8-9K (Bobcat + Rock) that was VERY well balanced on a dual axle flatbead. Togue weight was still well over the factory recomended limit. It wasn't pretty but it did the job over a short distance. Stopping was the scary part.
I tow a Ski Nautique (3-4K) most weekends with no problem. You can certainly tell its back there and I get about 8-9mpg. No surprise there! EXACTLY as expected.
I call TOTAL BS on your mpg while towing with your ****ty ford.
My Z71 Dropped 3-4 mpg towing my boat. For that matter, my Dad's duramax drops 2-3 and ITS A DIESEL!!
You should sell the H2. It obviously doesn't meet your "expectations".