Try reducing the cooking temp and taking a little longer.
I have cooked poultry at 325-350. Mine comes out fairly dark, but I'm fine with it.
Pellets and Pits YouTube channel just did a turkey cook to compare wet and dry brines. I noticed that his whole turkeys came out beautiful golden brown.
He cooked on a Weber pellet grill at a mere 250 degrees for a couple hours, then spritzed with oil and upped the grill to 350 when the turkeys were about 135. He says that it took about three hours with two turkeys on. He mentioned around the 12:00 mark that he usually cooks at 275, but he used the mixed cook temps to get a prettier, crispier skin.
You might try his approach if pretty skin is one of your goals.