The way people use EVs is a little different than how they use ICE vehicles. With EVs, you plan on stopping more often for shorter charges - you don't just run the tank down then search for the nearest station. Even a 1 hour charge will let you reach more local people because they can drive farther and charge a bit while enjoying your products.
So for me, the way I travel is to go from point of interest to point of interest, and since there are so many interesting places where I can stop, anything that differentiates one from another influences my decision. If you have chargers and those chargers are free to me, I will be stopping there - I will even be going out of my way or changing my route to stop there. Even if I am just traveling down the interstate, I would rather stop at someplace nice than to be stuck in a fast food parking lot while charging.
I don't think the chargers will necessarily help you get more local customers, but they will extend the region that EVs consider local. The market share of EVs is rising, so you will be reaching an ever-growing population. I personally believe we're near an inflection point - with something like 50 new EV models being released in the next two years, I think getting the attention of EV owners is a wise growth move. Plus the demographics of EV owners, being older and more wealthy than average, means that they are also more likely to be customers of your (I assume) more premium products. Of course if instead you cater to the Señor Frogs crowd, you're probably not seeing a lot of EV owners.
As far as the financial equation, we can't really say because we don't know what Rivian is bringing to the table. Are they subsidizing the charger or the electricity? Rivian chargers will definitely bring in Rivian owners and EV owners in general if they're free. What that amounts to in terms of cost of customer acquisition is really something that only you can calculate. I would guess that Rivian owners and Tesla owners at least would be inclined to leave with a bottle after a tour or a taste, and you easily cover your cost and maybe you gain a long-term customer that way. You know your business and your location better than any of us. Many breweries/wineries/distilleries cluster together to draw the weekend tasting crowd - having chargers would have somewhat the same effect even if you weren't particularly near any other tasting rooms, but you might also consider that having other businesses in your area that also have Rivian chargers would increase the chance that a Rivian owner would visit you. Getting on the radar for day-trips from Chicago could greatly expand your customer base, and having the charger is one way to do that. Plus, you know, help the climate a bit, which could fit into your marketing if you are a selling yourself as a regional distillery with regional ingredients.
With federal tax incentives (and local? I don't know about IL) I would be surprised if your pay-back time was more than 5 years. I think it could be much less if this strategy helps you grow. If Rivian helps you finance that, your up-front cost would be significantly less plus you could expense the payments rather than depreciate the assets.
