Bring in Non-Technical Partner?

It's not a product that will change the world, but it closely matches existing offerings in the market so I think it has a decent chance of generating revenue. Ultimately, I think it will come down to marketing execution.

I've been talking with a serial entrepreneur I met online who is interested in partnering. From my research he looks like someone whose career focus has essentially been online marketing and hustling. My hope is partnering with someone like this could drastically accelerate growth and unlock a lot of value.

I'm trying to figure out how to safely bring this guy in and test him out. In conversations, he's indicated that he sees this as a long-term relationship with us as equal partners. This partly makes sense to me, but other variables make it less clear. For example, I have been all-in for most of the last year working on this, and he will be joining with the product mostly built. Also, my leverage mostly decreases moving forward, since I'll have already built the product.

I'm hoping I can get some input on - whether I'm overthinking this or setting myself up for disaster - are there better ways I should be approaching this? - are there ways to protect myself going into this?