The customers you made money from when you're starting out don't have to be the same customers you make money from when your restaurant hits the big time.
At this point it's not about earning money, it's about not getting overworked to death.
Raising prices sounds like the best strategy. You keep raising until the workload returns to normal. If you feel you're serving the wrong customers, you now have time to figure out how to fix that. Otherwise, if people eventually get turned off by the price and your workload goes down, you drop the price, and keep dropping it until you reach a stable point with just the right amount of orders.
If clients have to wait hours for a burger, the existing clientele is gone either way. If you end up folding, the existing clientele is hosed anyway.
And as the original commenter noted, you could put coupons in the local newspaper and the library and whatever else, so the locals have access to burgers at the old price.
Or you have someone whose job it is to stand outside and memorize the names and faces of local patrons and turn away any newcomer who can't present an ID with a local address. You can have a second entrance for everyone else, takeout-only, with an hours-long wait, which plenty of food tourists will happily endure.
I think this is the point many people are seemingly missing.
Ask any family restaurant/bar owner in a seasonal tourist destination and they’ll explain why locals must be one of the first considerations before you make drastic changes. Particularly if an important reason for opening was a personal preference to serve locals over tourists in the first place.
It’s incredibly interesting to see how few people understand that someone may open a business with priorities other than massive growth potential.
