I don't think that you bringing your own gas is going to make anyone shut down. Most places in the Midwest that have fuel don't make a ton of money on it but usually do it so people have the range to make it to their business. If you are staying at the lodge and buying food there they will make their money off of that. However if people don't buy gas there they could end up not having it at all and then it would t be an option. Sometimes the reason for high priced gas is that they bought it when prices were high but almost anyone I have spoke to on the subject will blame the cost of delivery for high prices.
If you looked at the price of gas over the last 30 years, it is by far one of the best values for your money as far as items consumers buy. Even when it was $4.50 a gallon for 91 not so long ago.