Additional kudos on your first mobile home deal being one that requires a mobile home mover, vacant land, and transferring states compared to a simpler deal in a preexisting park. 

I wonder if the money in an LLC account, from rent but established before the rental house was put into it, can be withdrawn without being designated as a distribution but rather a return of capital pre existing before the house being rented was in the LLC?

It's a quirky part of the tax code, nobody at the IRS knows why it ended up that way, and we've been working to change that.In the meantime, if you want to get checkbook access of your pre-existing Roth IRA funds, setting up a Checkbook IRA will accomplish that.Also, for new Roth contributions, there are 12 key advantages you'll gain if you do them into a Roth Solo 401k instead of an IRA.

It's very manual, but I end up with an extremely high fidelity list and I'm able to exclude certain owner's/entities that I have a preexisting relationship with. 

Or your job transferred you and you need a home outside of your pre-existing commuting area (generally 90 miles)So if you are moving from one home with an FHA loan and you are moving up the street, and your family size did not change, then you would need to do a conventional loan.But if you refinance that FHA loan into a conventional loan you could get as many as you need.Keep in mind that if you used 3.5% down on a duplex, a conventional loan will require you to have 15% equity to refinance. 

Typically, the only thing lost in selling development rights is the right to build houses and all other pre-existing permitted uses remain.

Only reason question is being asked is due to a pre-existing seller timeframe required to close the first 4 deals that does not work with any lender's timelines.

Right now I only make money from my 1099 job, capital gains on the parcels I sell, and rental income from (4) pre-existing mobile homes.

@Graham Lutz You need to:1)have established relationships with deal sponsors and potential investors since this industry is SEC regulated and some of the deals maybe  done via 506 (b) = not publicly advertise and require pre-existing relationship2) have a full implications of each deal and be well-versed in syndications in general - people won't just jump on a deal cause you offer it.

Just make sure you are presenting this as a partnership and not a passive investment if you are marketing the deal to people you don't have a pre-existing relationship with.