Meet early and regularly with the lender or potential new lenders. You should be able to refinance the balloon payment with somebody if you can show them that the business is viable and executing. Hiring a CPA to express their opinion on the accuracy of the financial statements could be a good investment.
Don’t take risks in equity markets with any funds that will be needed to repay the loan. Especially if you’ve personally guaranteed the loan.
Go to a CFP, a legit broker like Schwab, or even the CPA if you need help on where to best stash excess funds. A good one should be able to assist with a proper compensation strategy as well (401(k), deferred compensation, having family on the payroll, structuring bonuses to minimize taxes, etc).
Interest rates are rising. Owning layers of bonds/CDs might be a good plan to accumulate the balloon requirements. Until rates have peaked, or at least leveled off, you probably don’t want to buy more than a year or two to maturity. The CPA, CFP, broker/advisor should have a good handle on what bond investment is appropriate. Be sure that they are a fiduciary so that they don’t steer you into investments that sacrifice your returns for their fees and commissions.