Not sure you will find any ONE specific person here to just do it all for you or mentor you step by step per say. What you will find here is people who are very willing to help with SPECIFIC questions. There are MANY different moving parts in what you describe and a few missing parts as well.
Honestly your best bet is to break it down into individual questions or steps. Also you need to finalize things a little more then you have described.
You dont mention what your data and possibly phone needs are for this system. Make a list of what you need this system to enable you to do... For example in my case when I was setting up my "list of requirements" it was to be able to stream 2 sd movies on netflix at the same time so my gf and i could both watch movies. I also had a requirement that I would need to me able to make a good quality zoom call (even if I had to stop all other internet access during the call). Lastly in my case I also needed the ability to make a decent cell phone call. I also at this time listed out a montly budget to try and stick to for monthly service fees and a budget for one time purchase equipment as well.
You mention an RV setup and dual carrier setuo but do NOT mention anything about external antennas or WHICH carriers.
You mention a modem but do not give a model manf or even if your interested in 4g or 5g.
You mention the netgear router but also mention an upstream router. Will this upstream router be a part of the rv setup? Are you hell bent on using the netgear and external usb enclosures or would your budget allow for a different router that could house the modems internally? People tend to be more familiar with the ZTE type routers so you might have a better exierence using one that others are more familiar with.
Budget..,. what can you spend on this...as i said above both one time purchase budget and recurring monthly fees budget.
It defintely can be a bit overwhelming but if you plan out in your head all the things I have mentined we can that get into the details of how to meet those criteria and the people in here are absoluetly AWESOME at that, but you have some work to do first