I agree. Use a highly diluted one shot developer for the second bath. Remember that if your paper were developed to completion, it would be near totally black (if not entirely so) in the end. Thus, your highlights are in peril at anything other than very high dilutions. Make it so diluted that it would not even fully develop a sheet of paper, in my opinion. To make a liter, I use 100mL of Ilford Multigrade working solution (which contains 10mL of syrup), and 900mL of water. This means the final liter of solution has only 1mL of syrup in it and 999mL of water; not even enough syrup to fully develop a sheet of 8x10 fiber.