It wouldn't be the only obstacle. Let's take wheelchair-accessible parking spots for example. We have to convince the store that sacrificing regular-sized parking spots (and the ones closest to the store, at that) in order to make room for a smaller number of larger parking spots that are reserved for 2% of their customers (and not exactly the most profitable 2%, either) is a reasonable accommodation.
Bear in mind that some of those spots we're asking them to convert might already be reserved for the store manager, some senior employees, and the employee-of-the-month as perks, rather than for customers. You will have a lot of convincing to do, and should expect significant pushback from the local chamber of commerce.