Probably the first thing you need to figure out is how you would get the wire to the outlets. The inverter should be near the batteries. Are the outlets close to the inverter or 20 feet away. Is there a solid progression of cabinets from the inverter to the proposed outlet to hide wire in? Or are you hoping to add the outlets to an exterior wall?
If you're thinking about exterior walls it might be easiest to run surface mount outlets and and channeling. This would hopefully limit the amount of holes to drill.
LinkLinkLinkYou would also have to buy the wire to go inside the channels.
You could also possibly drop the wire straight down through the floor and back up where you want the outlet. but you still need to protect the wire under the trailer.