Just trying to get a better understanding of the type of policy/agreements I need to cover all bases. 

Look for equity growth and purchase based off total ROI not just cashflow.

Based on this information what is the best path forward to be able to push to get the money returned in full to all investors.

If we were to turn our current home into a long term rental based on comps we would be in the positive around $700-$900 a month.

Although a metal building similar to Self-Storage in concept, totally different customer base. 25 by 45-foot bays, with 14 foot roll up door and a walk thru door, with light electric.  

Yes, the day 1 equity amount is increased slightly, but upon final draw, close to if not all of the down payment funds are recouped. 

If you use HELOC, it will have to be in 2nd position, where you can pull up to 90% LTV based on what you own on your current mortgage.

If I were to get my park back up and running, I would be adding the ability for the trucks to plug in (cut down on generator noise and exhaust - I would charge for access or build it into the rental fee, and most food truck operators would love this option), add real bathrooms, and add other features as an additional draw to get customers for the trucks. 

Your decision should be based on where do you want to be in 5 years 10 years etc.

If going with a full custom plan (e.g. you have a unique lot layout that will require a customized layout)… closer to $10K, including construction drawings, title 24 energy report & electrical layout, permit processing-Permits: $5K is typically what the total costs to the city will run for an ADU, even with the waived feesConstruction costs: $250/sqft + $10K-Building costs: typically $250/sf to start, for vertical building only.