As I recall, the scale was eight million dollars in one month. I'm with you that a sleepy rural hotel can't handle that. However, charging fraudulent expenses

As I recall, the scale was eight million dollars in one month. I'm with you that a sleepy rural hotel can't handle that. However, charging fraudulent expenses to the same sleepy rural hotel can't fix that problem. (It aggravates it!) The hotel can't spend more money than it has. And if you can make it look like the hotel has enough money to suit your needs, your job is already done. Fake expenses don't help. After a long time spent on various dramas related to this initial problem, the show addresses it by having Marty found a casino, which seems plausible.