If the numbers don't work for expanding the building, explore the potential based on the current space. 

We only have one small property, so I manually adjust the price based on what I see for the month. 

Tiny house thing doesn't make sense to me btw because tiny homes aren't really good for appreciation, maybe only for cash flow.

We had been negotiating for weeks, during which he asked me to draft the offer based on his price and terms and requested over a week to review and accept it, which I honored.

I have ideas of the values, but nothing based on anything concrete.If I take out a construction loan, how do I pay for the construction loan during the process? 

The price paid is well below what we should have paid based on number of lots/homes/ that can be built.

Permit eligibility is based on region (usually the west side of town) and density (quantity of surrounding STR's in the area) as well as percentage of landscaping and minimum parking requirements. 

I want to use my current home and do a HELOC.  

One said the 2nd mortgage has to be assumable and the other said it did not.VA issued Circular #26­24­17 back in August to try and clear up the issue:Assumability: If the secondary borrowing is not assumable, the holder of the VA guaranteed loan should counsel the assumer that this may restrict their ability to sell the property to another creditworthy assumer through an assumption in the future.The lender currently servicing the loan still can decide whether or not they'll allow the 2nd.You could do seller financing for the gap and then refinance just that amount with a Home Equity Loan or Line of Credit at some point down the road. 

There’s probably a legal notice period for that too, based on your market.