Storing on the water realistically means you are setting up a bird sh*t platform on top, weed-growing fad underneath, to be blunt. The bottom will need to be antifouled, so you have immediately lost speed, and it just gets worse as you scrub off and re-apply each coat. And is expensive, plus needing somehwere to clean and paint. As for the top, well, sitting out in the sun on the water ages them faster than anything, and you will need to put on/take off a full length cover every time you want to use it, or it will be full of the above-mentioned bird product.
Do you really have a problem with a trailer or storing on land?