I think you should focus on what’s best for your typical crowd today, then worry about adding on later.
I don’t pretend to to about her business, but I know there’s a lot of great small speaker options that will provide crystal clear music with enough bass for those crowds. Everyone will have their opinions on how much exactly is enough, kind of like picking a favorite color.
She should get the best really portable speaker she can afford...or the business can afford. It needs to stand up to the road and still sound great. I don’t care how tough she is, lugging around heavy speakers and subs will make it MUCH LESS desirable, especially when she goes somewhere else and hears great sound coming out of a small speaker, and then wants to go BACK to the store.
Personally, I’d go with a l1 compact, s1 pro, or an EV.
But just for reference, you mentioned you thought the L1s was lacking. In my experience, that one is WAY more than you need.