Solar Install: what would you change

Flexible panels are VERY inefficient and are prone to breakage. Rigid panels are a much better choice. They are more efficient, less likely to break/stop working and have much longer warranties. I’m not sure what you mean by semi-flexible, but if you are referring to the panels that can contour to a rounded roof, these are the inefficient panels I mentioned. If you use 12 volt panels, there is no reason to use an MPPT controller. MPPT controllers are intended for higher voltage panels. They take the extra voltage above 12 volt and turn it into additional amperage going into the batteries (assuming a 12 volt battery bank). If the panels only put out 12 volt (or very close to 12 volt), there is no benefit to using MPPT. It is always best to design your system to handle possible future expansion. Use larger wire than you think you will need. Use a solar charge controller rated for more capacity than you need, etc. This will cost a little more up front, but will make it much easier and cheaper to expand the system later (and almost everyone wants to expand their system once they see what solar can do for them).

I have a very large solar array (1410 watts) on my 5er with a large battery bank (1040 amp hours). All of my components were sized larger than needed. This was not so much for future expansion in my case, but to improve efficiency. Think of electricity like water. The larger the pipe (wire) it flows through, the easier it flows.