I was hoping someone would have a recommendation for you. You could try your question on the Class B section of RV.net - http://www.rv.net/forum/index.cfm/fusea ... rum/21.cfm
I'd definitely get a professional to install propane if that is what is needed for your stove.
Adding a second house battery is not difficult. Consider having it mounted to the van frame if there isn't a compartment available.
I mounted two of these trays:
for extra batteries.