How can I limit the volume on integrated amp

Just by a nice sounding Bluetooth speaker or clock radio like Sandals does and put it in each of the rooms. I use to be a property owner. The only people who care about your property is you and yours regardless of age or income. Lock the nice system away on the property for yourself for when you are using it. My uncle did this with his primary residence. He had a closet that he locked up for personal things. 

for you, for a few weeks a year, think that thru.

a closet with a lock, a critical piece of your good system locked in there so it cannot be used. note that it is disabled so they don't try to get it working (I would).

a bluetooth speaker they can link to, not too loud.

renters can turn the tv up enough, run pandora, link phones, so leave a note asking them not to exceed _____# on the tv set volume.

Rotel RA-12 or its predecessor RA-11 have menu setup for max volume, by input, Bluetooth, and are workhorses.  Can be found on used market in all probability.  Throw in a Sonos Connect and you'll have very happy renters.