roscoe1, are you sure nobody is using snorkels, because the latest tanks come with them. You are restricted to 140 knots with the snorkel though. 150 without snorkel with belly tank.
Goodrich landing gear is an option on the 139 and increases the ground clearance by a good 6-9 inches. Bigger mainwheels too, so soft ground operations are better. Extra ground clearance is nice to have with the belly tank installed!
Simplex Aerospace Fire Attack helicopter belly tank model 326 for the AgustaWestland AW139 brochure and pictures