Ideally we would like to avoid paying someone's mortgage, but is investing while renting in our current location a wise move? 

There are obviously fake accounts offering ridiculous terms that stand out like a flashing neon billboard.Also, the countermeasures are pretty simple: "Don't pay anyone for ANYTHING up front!"

I have a stable and relatively high-paying job with savings and I’m ready to invest.

They aren’t moving to pay the same.

With LLC we pay the $800 CA franchise fee every year, correct?

If this tenant is actually a friend, surely they'll understand your position and either pay the higher rent or find another place so you can get up to market rents.

You'll probably need two years of tax returns of paying taxes in USA to qualify. 

The tenant who wants to return has also been a very good paying and clean tenant.

I joined bigger pockets a while back but had to focus on paying my way through school and passing a dual major in Chemical Engineering and Paper Science Engineering.

That said, I know a few MHP operators that make some pretty tremendous money on the trailers, mostly by renting to people who need to pay in cash and have someone not ask a lot of questions - illegal/undocumented immigrants, transients, probably some criminals for sure, sometimes people (mostly women) hiding from domestic abusers, etc.