Tried home depot project loan and was only approved for 5k.

Ask them for the approved budget, if they are behind on bills thats a red flag which will lead to special assessmnets.

I am pre approved  for an fha loan through a local lender.

My advice would be to first find a lender and get pre-approved.

(This route I have questions on) Bring in a partner for loan approval purposes only.

Because an un-collectable judgement isn't very useful, nor is $3.00 a month for 10,000 months or some other such pecuniary payment scheme approved by the court.Good Luck! 

And since you won't have any approved engineered plans, they'll still be just guessing, so you can have these bids come in 20% off, easily.

Even if you sell the land the developer will want to go thru most of the process before he settles on  it , unless you come to other terms . 18 acres down the road from me took 10 years to complete the paperwork from zoning , engineering and county approval for town houses, it was just approved and now an appeal was filed , that sets them back 6 months .

I cant get approved for a loan (I’m self employed/ no consistent w2s).

My property management company took care of all of it for me after asking for approval, and it was one less thing for me to worry about.