I'd see about snagging a backup pump assembly from someone who has swapped out their toilet and is looking to ditch the Thetford. It's worthwhile to have for $50 or so. Also I'd look to get a pair of the white plastic hold-down clips that secure the toilet to the floor. These were hard to find at one point. I agree about the seal kit and tank seal (I just replaced both on a toilet I'm "remodeling")...
https://www.trailmanorowners.com/for...ighlight=clips