The size of the PVC pipe to be used for an RV sewer should be 4 Inches, and since standard RV sewer hoses are 3 Inches in diameter, you will need to use an adapter. This adapter will transition from the standard 3 inch black water connections on the RV to the 4 inch threaded PVC.

How do you install a toilet flange on an RV?

0:102:33Review of LaSalle Bristol RV Toilet Flange - 3446336347 - YouTubeYouTube

Is RV toilet flange same as home?

The floor flanges are the same but I would advise against doing this. A household toilet has a top tank lid that will rattle and break. it must be removed. A household toilet will not stop water from sloshing out as you go down the road.