Are you a local boater or make long runs. I ask to point out, Local boater can keep his spares off the boat. I have two places on our Bert, depending on trim requirements, under the master bed, aft and to stb, or forward bilge, forward center. 32x32 have some weight to them and there location does help with long range trim.
I agree. You need both. I store mine on a board on top of the water tanks acessessible from the lazarettes
my spare wheels are in the garage on land. I guess if I was extensively travelling I may put them on the boat.
My 1982 42' Post looks to have a factory installed storage area for spare props under the cockpit. Like PORTHOLE says, the storage area is located under the cockpit floor, outboard near the transom and under the fiberglass exhaust tubes.