Yes... you are right. It's an absolute great way to ruin a friendship. And... an older seadoo boat is not the "User friendly" rental type boat. If it was a newer 4-tec boat... it would be a different story.
I have 2 buddies that can use my jetskis whenever they want. I trust them, and they will take care of any damage. But... I have a lot of other friends, that can't take them. But, even though... I let them out... I remain the owner. It's just easier that way.
With that said... your agreement looks complete... but I would change a few things.
1) Make it mandatory to trailer with the cover on. You say to keep an eye on the seat... but if it comes out at highway speeds... it's going to get destroyed. If you have a good Poppy cover... it will last for a bunch of years, and will save a lot of issues with missing items, and road damage. Just make a new cover part of the maintenance $$$$.
2) Don't leave it on a trickle charger. If it's being used... then there isn't any reason for it. And... that also takes worry out of damaging the MPEM.
3) Oils: Any good, synthetic API-TC oil is fine... but you still don't want to mix brands. So... I would suggest that you (or the primary owner) buy a case of oil, and stash it in the storage box for the other users. That way, you will be safe, and there wont' be a failure from mixing oils.
4) The check lists are good... but people get comfortable, and things get missed. I would highly recommend making a small portable version (versions) and putting it in the boat. That way... the other user(s) won't have an excuse to not use it directly. Along with that... I would put a big sticker, or laminated list, right by the trailer handle, that says... "1) are the transom straps off? 2) are the plugs in?"
Good luck, and let us know if it actually works out.
