The thetford toilet in our RV has a ball valve, instead of a flap. I don't know what the seal life on it may be, but odds are that daily use is better than letting it sit. Look at all the full-timers with those things.
I had a boat with the toilet and shower, and bathroom sink all in one footprint. I loved it! You could just spritz the whole compartment with a little simple green, hose it all down with hot water, and leave it to air dry. The "head" was always spotless, and the shower sump always clean. A little windex on the mirror and porthole occasionally and it was good to go.
I couldn't get away with that sort of setup now, with the wife and kids, but I sure liked it for a bunch of fishermen.