Answer: We suspect that there are RVers out there who may have done such a conversion and hope they will chime in. We have a combined microwave/convection oven, not a gas oven, and have no personal experience in making such a change to a gas RV oven.
Our initial thoughts regarding replacement of an RV oven are that you would need to consider what modifications are needed to physical space and layout in the kitchen area.
You can search for possible replacement units online or go to RV supply stores. You may want to contact PPL RV Parts Superstore (800-755-4775) to see if they carry ovens, and/or try the individual oven manufacturers (Suburban, MagicChef, Atwood, etc.).
Depending on the amount of work involved and how handy you are, you may be able to do the work yourself. Otherwise we would try an RV service facility.
We invite comments from other RVers about converting to a larger gas oven.