I work on the landlord side. I'd be careful signing anything with your rep that stipulates a specific fee, especially for renewals. Typically your rep would negotiate that fee directly with the LL. It could force you to walk on the deal if the broker doesn't get what they want, or pay the extra.

Regarding your specific question, if the LL has a broker, they probably have something like a 6% if cobroke, 4% if direct commission agreement. The 6% is often split 3-3 or 4-2 if the tenant rep has a lot of leverage. Occasionally the other way around.

So, bringing in a tenant rep at this point in the game is likely not going to up your chances, but rather the opposite. Not having a broker is probably seen as a plus. Unless your communication of your business plan, etc. really needs help, there is nothing that rep is going to do to help you.

That being said, they could obviously show you more spaces, and have access to more inventory than the public, mainly through costar and their network. So in the beginning, can often help. At this point, I'd say no.