Toto has bolt down lids for the Drake models.
I just installed a couple of Toto Aquia's in my home and I'm very satisifed. I also have a couple of rental properties where I have to pay for water usage. I am considering replacing the old 3.5 gpf models but noticed many tenants use those tank tablets that corrode the working parts. Yeah, I've tried putting restrictions in the lease terms but that hasn't fully worked.
Does Toto or someone else have a kit to make the tank tamper proof to prevent people from opening the tank? I thought I saw something from Caroma but don't want a Caroma toilet.
Here's another thought. Raise the damage deposit and tell the new tenants that tampering with the toilets will automatically forfeit the deposit. Assure them that if there is a problem they should call you immediately and not attempt to fix it themselves. Make sure everything is in writing and signed by both the renter and yourself.