Tools- I guess I'm the one that's crazy

I'd make it clear to him that you are doing him a favor by storing his stuff in your place(s) and that if he doesn't like the terms of storage---that there may be a wait on retrieval since some of it's off-site---then he's also welcome to, in no uncertain terms, store his stuff somewhere else.

I'd probably tell the SIL and wife the same thing so there's no confusion on how it works. :D The SIL is welcome to store his stuff if she doesn't like the terms, either.