To plug up the hole from the standard RV toilet go to a full service plumbing supply store. They sell expandable plugs that will seal off the hole without having to modify your RV. Then use the toilet bolt locations to secure a small riser platform on which you can secure your composting toilet.
If you have never been involved in remodeling or renovating old houses you won't know that there are such options. So when you come across these unusual situations with plumbing just head to your local plumbing supply house and talk about your needs. They very likely will have a solution you can use as is or modify for use. The people at Home Depot and such do not always have the knowledge but a good plumbing supply house often handles odd situations. When you do go there first remove your toilet and take a measurement of the diameter of the drain tube to your tank and you can even take your RV toilet along in case you need more measurements such as the size of the seal, the size and distance between the toilet hold down bolts. Take some photos as well. The more information you can provide the fewer trips to the plumbing store. But remember it will always take more than one trip, plumbing is like that
Fortunately I enjoy prowling around hardware stores and other types of supply stores such as electrical and plumbing. Having done a number of house remodels I have seen a lot of different kinds of parts used for installations and repair. Not an expert at everything but not clueless either.There are many variations in how the different makers of RVs handled the details of how they created the floors that support the toilet and how they attached the drains underneath of them. They are not all going to be easy to work on, but none of them will be impossible.
If you have never been involved in remodeling or renovating old houses you won't know that there are such options. So when you come across these unusual situations with plumbing just head to your local plumbing supply house and talk about your needs. They very likely will have a solution you can use as is or modify for use. The people at Home Depot and such do not always have the knowledge but a good plumbing supply house often handles odd situations. When you do go there first remove your toilet and take a measurement of the diameter of the drain tube to your tank and you can even take your RV toilet along in case you need more measurements such as the size of the seal, the size and distance between the toilet hold down bolts. Take some photos as well. The more information you can provide the fewer trips to the plumbing store. But remember it will always take more than one trip, plumbing is like that
Fortunately I enjoy prowling around hardware stores and other types of supply stores such as electrical and plumbing. Having done a number of house remodels I have seen a lot of different kinds of parts used for installations and repair. Not an expert at everything but not clueless either.There are many variations in how the different makers of RVs handled the details of how they created the floors that support the toilet and how they attached the drains underneath of them. They are not all going to be easy to work on, but none of them will be impossible.
