Re: Sailable projects?
Finding a location to store a propane tank on a 22' boat is difficult. Your only option is probably the stern pulpit railing, which will likely already have your swim ladder on one side and access to the outboard on the other side. 22' boats are pretty small and you want to keep things really simple to make best use of the space.
You also need to add a fuel shutoff solenoid and sniffer. It is an expensive system when a simple unpressurized alcohol stove (Origo or one of the knock offs) works so well.
The danger with doing propane incorrectly (just using a camp stove in the boat for instance) is that propane is heavier than air and will collect in the bilge. You'll probably have a bilge pump there and when that turns on explosions can happen.
I live in Seattle (where 80F is hot and 40F is cold) and have never considered a cooling system on a boat, so I have no advice or experience there.
boats that I sail on regularly: Pearson 28-2, Rondar 505, Yankee 30, Blanchard Junior