How to avoid getting screwed?

[Armaan H.]

Have been keeping an eye on some vacant land near where I live (Chicago, IL). Former auto repair shop. Current owner demolished the building and did a Phase I, which came back clean. Original plan was to build a Starbucks with a drive-thru, but the City didn't approve the special-use permit required after strong opposition from neighbors who were concerned about traffic congestion, pollution, litter, etc. 

Starbucks withdrew its plans because the proposed site was a relocation of an existing store nearby. Without the drive-thru, it wasn't worthwhile for the coffee chain. Not to mention bad PR. Owner is asking for $600,000, but the RE broker said the seller is definitely willing to negotiate. I can easily get for $500,000, if not $450,000.

Here's where things get interesting. There's a Popeyes franchisee that's looking to add more stores in the area. The guy operates about 3 locations in the area. The nearest Popeyes from the site is 5 miles, which is owned by the franchisee I'm referring to. I reached out and he said he would happily be a tenant if I find a location he likes.

Based on my quick-and-dirty analysis, fair market value is $80,000/year NNN ground lease. Conservative 6% of sales. The CAP rate would be at least 13%-18%. Wouldn't mind holding or flipping.

So I have a location and tenant identified. Property is under contract for full asking price (will negotiate once Popeyes approves site). 120 due diligence period with multiple contingencies. No earnest money, but showed partial proof of funds (which would be down payment to lender). 

Since there's a HUGE FOR SALE SIGN on the vacant lot, how can I prevent being bypassed when the franchisee is given the address to do a drive-by?