For clarity, Im assuming the OP is still using the Chevy minivan that is being customized.
If so, that doesn't lend itself very well for carrying a generator and gas can unless an exterior storage solution is installed.
Solar would be the easiest solution, providing noiseless, CO-free power. If considering this rig for the long term, a battery isolator with good connection to the house batteries would also be a good choice. The isolator will separate house batteries from the chassis battery and allow charging without drawing down the chassis battery.
A month of driving to a repair shop and paying the expense of battery charging would pay for a small solar system.