What Gritz said.
Here's what i would do (you lucky, lucky guy!)...
Easiest to run a pos & neg off the House battery
Put in-line fuse on the positive lead
Then split to both storage boxes using the existing entry point for the storage box light
Use zip ties along the way
Then re-seal entry holes with silicone sealant
Go up thru the floor
Use a minimum #12 stranded wire & use a crimper tool to properly fasten connectors to Batteries
Then the magic happens!
Keep us posted and send us photos.
'17 Vegas 24.1