Brokering a long term billboard lease

I may have the opportunity to identify and broker a long term lease for a municipality with a major billboard company. I have identified the opportunity and the ability to bring a substantial lease proposal to the town.
What would be considered common fees or commissions to receive from a major billboard company for such a transaction. I have done the research on what the average monthly gross income would be for a billboard company in that area.
Would the fees be for the length of the lease or a one time fee?
If the lease is in a A+ location and over 25 years does that ad more value to the fees and or commission?

Are you being compensated by the town or the billboard company?

We would be compensated the billboard company

Then your best course of action is to get the permit and then sell the lease and permit to the highest bidder – play off two or three of the largest players against each other, just like an auction. There is no guideline to what you can get, it’s completely negotiable. I would let the market set the price through an informal “auction”.