For lots of reasons I was never good at boundaries.
Setting one simple one and learning to stick to it for the last 3 years has helped us a lot. That I had rights to my sitting room and piano. He had 2 others he could use at any time of day or night which he did. I was a real jittery mess at the time. I had inadvertently let him rule the roost. That it was only one boundary, but an important one, helped me gain clarity and some sense of entitlement in my own home. It was easier for my son with all his jumbling intensity to eventually stably stick with it, even though he tested an awful lot. Now he knows he has to book in to have the grand piano room, if it did not suit me, I could say "no". Before it was all adhoc and I became a total mess and retreated to my bedroom. It took a year on the forum, grappling and researching widely online to find an approach.
Hearing you @Tufftimes re managing 2 adult males with Aspie and schizoaffective disorder. That is HUGE. You have got your hands full. I also find the zoo helpful, setting boundaries or making observations about animals ... not in a mean way, but in an essential, this is what makes us tick ... or not tick ... way.
Take Care
Apple