Mobile home park investing requires specialized knowledge and experience that is unique to MHPs, so it will be good to become adept at the following:Finding deals - You will need to be adept at sourcing parks to acquire.

I am really looking for recommendations on a broker that specializes in this niche, not just looking to get anyone's attention.

I would write a list of all possible niches, then first cross off the ones you simply could not do.

I bought a unique property in LA a little over a year ago with the intent to Airbnb it, only to find out that it is 100% illegal to do short term rentals.

I've read here that we'll probably have to explore different investment options to find out niche.

Then my next major decision is what niche to zero-in on (And I don't even know all of the different ways to make money off REI yet).

If that's a dedicated niche that you're focused on, search the big-box sites for any and all 2-4 unit properties. 

I'm leaning towards BRRR niche and I look forward to getting my first investment deal.

There are a few things you might consider doing after you select your niche and market area.One of those things is to form some type of corporation or a LLC.  

And, yes, insurance appears on IRS Form Schedule E:I, of course, and not a tax professional, and am not up to speed about what might be unique to your particular situation that prevents being able to write these things off.But you might want to consider hiring a better tax guy, if you're being told that you "can't ever" write off property taxes!