See we run at over 40 with the bimini up. Honestly I don't even look up at the speed but its still there when we slow down.Both of my boats. (Searay 220 Sundeck and Tahoe Q4) use Saddles mounted with screws fastened to the deck in front of the winds...
Think about cutting a hole in the top and using the existing tank as a surround for a new gasoline bladder. I've never done it but it sounds like a good, safe & permanent solution to old alloy fuel tanks.
How hot are your risers getting? I presume its raw water cooled or is it fresh water cooled? You do need to have a good engine circulation pump and impeller. as they work together. A temp. gun is cheap on Ebay and can help look at what is getting hot...
Expensive and nice. Find a good mechanic who is recommended. You need good 12v power, HD windlass breaker, big hole cut into deck - make sure its reinforced (between deck and ceiling), battery cables run etc. Make sure engine is always started and al...
Easy fix. Rent two carpet blowers and pressurise the cabin with a temporary plywood door. You find more leaks than your 100 yr old grandpa had mistresses. Spray soapy water on the outside. You will be amazed.