Living out of a vehicle full time is *Very* different to holidays or weekends.
As has been said, you really need to decide *how* you want to live & travel. If traveling mainly for short periods & staying put in one place for months at a time, your setup will be quite different to one for regularly moving on.
Eg. If the former your existing tent may suffice if it's tall enough to stand up in. If the latter a rooftop tent would be preferable as a permanently made up bed makes a huge difference.
An awning is an essential. You will be in many places where it is the only shade you'll have.
Your fridge & compressor will be 12 volt, so an inverter will not be necessary.
IMHO dual battery systems are easy to set up yourself. Buying a ready made dual battery system just costs more.
Cuppa