300k+ a month in bonuses is a lot - I tend to sign contracts without bonuses, doe.
Really, that's a pretty common balance sheet for most clubs. In order to stay competitive, they have to overpay in salaries what they can afford. If you are successful (which you have been so far), you'll be okay with prize money, increased attendance, bigger sponsorships, etc. If not, you pile on the debt, lower the wage budget constantly until ur finally relegated.
Luckily, ur the former so the prize money from the league will keep you about even for the year.