What type MH/RV are we talking about? If it is in good shape.
I have almost the same toytie a 1982 Thetford Model: SH/SA Aqua Magic toilet. We watched a video on repairs to it and it was a breeze. 2 Bolts to remove off floor and the hook ups take outside and give it a good cleaning I used Bleach white for tires and it worked great just like a new toytie, replace the Flush valve is all there's too it. buy a new floor Flange and try working the foot lever to see if you can get the seal to reseal spray a little wd40 or a lube of some sort on it and let it sit awhile working it in with the floor lever. I think total was around 35 bucks for all parts except for that seal. If I remember you can go to Thetford and watch a repair video I am pretty sure.
1982 Pace Arrow P30 454
KarKaddy SS, Toad: 2009 Genesis
Tim, Joe and Lilly too. Mpls Minn.