I am converting my PriusV into a stealth camper, I need more information about how to integrate more batteries and charge from the generator. PlsHelp?

As stated above I am converting my 2014 Toyota Prius V into a stealth camper. I am planning on purchasing 1 or 2 Battleborn 100Ah LiFePo4 units, 1 or 2 Rich Solar flexible 100W Solar Panels. I already have a EPever 40A Solar Charge Controller, 2000W Whistler Pure Sine Wave Inverter, and a Stinger SGP32 200A Battery Relay Isolator. One method of charging I’ve thought of is to maybe get a DC to DC charger and plug it into the 110v plug on my inverter, but I think I like the idea of having it built in better. It seems like it’d be a bit more ”finished” feeling, but I’ll do what I have to. As for my “loads” I have a generic China brand 54qt 12/24v domestic freezer/fridge I bought on Amazon which I assume will need to run 24/7, I need to charge my devices such as my tablets/phone etc. at night and I also plan on purchasing a 12v electric sleeping mat for the winter because I live in Chicago. I guess what I’m asking is if I can wire my system up just like an RV or if I’m going to have to jump through hoops because of Toyota’s propriety 12v battery system which is only a 45Ah battery. I contacted Battleborn and they recommended that I didn’t wire it into my system. So could I just do the DC to DC thing for a bit of emergency power? Any help is very welcome and I thank anyone in advance for your response. I can read electrical schematics so that’d be welcome and would really help in me understanding exactly what you mean. Have a Nice Day?