Hm... under current law, the cryonically preserved are considered dead, and thus any contracts they signed are no more enforceable than a contract with a graveyard to perform one form of burial instead of another. The existing cryonics companies have standardized contracts. I can't think of any way to create the contract you describe. Do you have any further details in mind?
I wasn't concerned with the legal details, which will vary from time to time and place to place. At the moment, what obligates Alcor to keep their bodies frozen?
And there are wills. You can already will your body to medical research.
This thread is for asking any questions that might seem obvious, tangential, silly or what-have-you. Don't be shy, everyone has holes in their knowledge, though the fewer and the smaller we can make them, the better.
Please be respectful of other people's admitting ignorance and don't mock them for it, as they're doing a noble thing.
To any future monthly posters of SQ threads, please remember to add the "stupid_questions" tag.