You have a receivable of USD 25,000 coming in 6 months and want to guarantee you’ll end up with THB 850,000 in the end (at the current exchange rate of 34).
The way to do this is to take out a 6 month USD 25,000 loan, convert it to THB 850,000 and put it into a 6 month time deposit. Then, 6 months later when you receive the USD 25,000, you pay off the loan and use the interest earned on the time deposit to help defray the cost of borrowing. Hedging is not without some cost, but this is exactly how to do what the OP is asking.