Even with obese people now being classified as disabled, wouldn't that mean you could still require them to "modify" your unit to, for instance, a bariatric toilet, and then modify it back to normal, or be able to hold them responsible for any damage they do to the regular toilet or plumbing if caused by their weight?  

Feel free to modify it to match your rental agreement terms and landlord tenant law for your jurisdiction."

Otherwise, it seems that landlords can just modify the MTM lease in any number of unreasonable ways to make the tenant move out, and thus raise the rents.

I always try to modify my business processes if I find something that is not working for me. 

@Brandyn Dietman  I'm a little late in adding to this discussion, but you may want to download our "Rent Past Due" letter from the BP File Place and modify it for your own use.

I don't know California law, when is the next opportunity to modify the lease? 

Irrespective of when the old tenant moves out.But the above described is a new agreement between two contracting partners (here: landlord and tenant) to modify the existing agreement (= lease) and nothing else but the rescission of the lease agreement based on this new agreement.Long story short: anything can be done between two contracting parties if they agree (barring some exceptions via compulsory law, of course).

You can modify it for your own needs.

This general rule may be modified by some form of agreement, whether implied or written down.

I can do many rehab jobs but I don't know anything about structural stuff (so I hire an engineering company to put their name on the line before I modify structural).