I converted the 12v system in my Jayco Freedom pop-top into an off the grid setup to suit my needs. This whole setup fits underneath the small bench where the outdated setec unit is which I replaced with more efficient components and a single fusebox. I believe anyone can achieve this and save thousands $$ in installation costs by doing sufficient research into how 12v systems work and which components will suit your needs.

The components in my setup:
Enerdrive 200ah B-Tech Lithium battery
Enerdrive Dc2DC charger
Victron smart blue Ac charger
2 x 180W Enerdive monocrystaline solar panels
Kings 1500w inverter
Jaycar shunt with battery monitor