I think you should technically be able to use the publicly available functions to fetch the wallet's master key and derive any address type at any derivation path you want but I don't think it is possible to make it part of the wallet file itself. Because that would require modifying the wallet file (something that a plugin should not do) and that's something that would corrupt the wallet because it is designed to have a single "type" that the code uses to derive child keys. To change this last part you'd need to change the code.