I don't want to just sell off part or all of the land to the developer because a) they'll likely wreck the vision (actually revitalization of the city) and b) want to make all the money.

I could rehab and refi to recoup some or all of the renovation expense however rates are low enough now I may be subject to higher rate when I come back to refi. 

Even if your neighbor meets all the WA requirements to adversely possess a portion of your land, a recent change in WA law (2011) requires that the adverse possessor repay you a prorated portion of the property taxes for the land they adversely possessed.RCW 7.28.083Adverse possession—Reimbursement of taxes or assessments—Payment of unpaid taxes or assessments—Awarding of costs and attorneys' fees.(1) A party who prevails against the holder of record title at the time an action asserting title to real property by adverse possession was filed, or against a subsequent purchaser from such holder, may be required to:(a) Reimburse such holder or purchaser for part or all of any taxes or assessments levied on the real property during the period the prevailing party was in possession of the real property in question and which are proven by competent evidence to have been paid by such holder or purchaser; and (b) Pay to the treasurer of the county in which the real property is located part or all of any taxes or assessments levied on the real property after the filing of the adverse possession claim and which are due and remain unpaid at the time judgment on the claim is entered.(2) If the court orders reimbursement for taxes or assessments paid or payment of taxes or assessments due under subsection (1) of this section, the court shall determine how to allocate taxes or assessments between the property acquired by adverse possession and the property retained by the title holder.

Matter a fact, the PMs revenue model benefits if they place a turd that needs to be evicted or is consistently late or all 3, needs a lot of service calls to boot.

To reiterate the points made by @Steve Mcmahel, depending on your employer plan, you may be able to roll either a portion or all of your 401(k) into a self-directed IRA.

in your opinion.Rent the pads and don’t have any POH’s (Pad Rent Only)Rent the pads and convert some or all of the park into Lease/Purchases POH’s (Pad Rent, Monthly Lease until Purchase)Rent the pads and fill with POH’s (Pad Rent and POH Rent)I know that these can a bit subjective and also can be mixed and matched as needed.

You can see how this could consume much or all of the RE appreciation on such a short term hold.  

(There May be other setups, but that’s the 3 I’ve encountered.) sometimes, some or all of this can be handled online but you have questions about the current setup so talking to a person can’t hurt.)

Is there any risk of loss of any or all of your investment if they can’t complete the fundraising?

Build one at a time or all at once, depending on captial constraints.