I too am new at this. The proper way to design a system is usually done by figuring the calcs on your load side, then picking a battery and solar setup to meet those. When I started this, I had no load side yet. So I started in the middle, knowing I would be adding loads and solar. I am in a rental house so no perm. installation for me. And, I have cabin on on a few hundred acres that I use. Plus other camping.
I knew I would need portable, to move around to different scenarios. If you look at the videos of home installations, I basically took everything off the wall, and placed it in a large pelican case. The 70 amp hours was a size that would also fit in the case, and still be portable.The idea being the case would work for camping/cabin, and could also be used at home. It contains a morningstar controller on one side, two battery posts in the middle, and a Morningstar Sunsaver Duo on the other. The duo was chosen as it can charge the case batteries, and whatever second battery I plug in. I have both truck batteries wired to the back of the truck, the starter battery through my 7 pin trailer plug (which is always hot) and my 2nd vehicle battery through a large anderson that may also see a portable winch in the future. The plan being the case can go wherever I need it, and I can currently use/charge any combination of the three batteries I have now. My second truck battery is only 55 ah, so it is small, but has no dedicated load on it.
The case also contains 4 13 watt Goal Zero Panels and their Nomad Sherpa 50, that I could grab those out of the case, and have my backpack solution. Or when lots of folks show up at the ranch, I could loan it out to folks to charge their small devices. So yes, I am small on any one battery for my portable, but combined it should be enough for my current situation. As the case will also serve duty at home as a backup to my house needs, primarily my freezer if the power goes out, I will probably add some decent battery storage here that will sit in a closet. And I know a lot of redundancy here (and cost), but the upside (combined with the upside of learning how to put it all together) gives me no worries about losing one part of the system, and being entirely down.
As to inverters, I have a small samlex pure sine 120 in my case. This is plenty big for portable, for electronics or small power tool recharging, say up at the ranch, where there is no power. Creek and outhouse affair. Here at home, I got a cheapie 1000/2000 from Harbor freight that can run my fridge or freezer (not at the same time). I also have something similar in my truck, that used to be in my Jeep. Other than the home frdge/freezer, not a lot of need for AC in my uses. If your camping requires a lot of AC, then you most certainly need bigger battery/solar/inverter than I have designed.
It is easy if you have your loads, your camper/rv and lots of room. When you are not sure where you are going with all of this solar stuff, it's a lot harder to jump in. And to reiterate, this is all new to me. I probably will have changes as I learn what does and does not work. The good folks here on this site have a lifetime of experiences and posts to help make the decisions easier. I tend to post little, and read a lot. My new Arb fridge is going on its maiden voyage this weekend, and the monsoon season has hit here in northern NM, so I am right off the bat going to have shorter solar hours. We shall see......
Craig