I've never grilled turkey, but this is how I roast either a whole turkey or just the breast. I see you have a skinless one....so you won't be able to put lemon or orange slices under the skin

but you could put the rest of the stuff on it anyway. I would definitely roast it covered since it's skinless! I do anyway, but the directions never tell you to do that.
Betty Crocker says 2.5 - 3 hrs for a 3 - 5 lb boneless turkey roast. Cooking it covered always cuts the time dramatically....sometimes in half. I don't think it will take all that long to do yours.
Kosher salt
½ - ¾ tsp lemon pepper
1 tsp thyme
1 tsp ground celery seed
½ tsp lemon zest (I use dried)
¾ tsp orange rind (I use dried)
2 3 oranges or lemons
½ c orange juice or
¼ c lemon juice
Cut 1 orange (or lemon) in half & squeeze juice over outside of bird. Set the squished pieces aside to toss into the cavity after rubbing with spices.
Rub inside & out with Kosher salt.
Combine spices & rub this mixture inside & out.
Toss squished halves into cavity.
Slice 2 oranges (~¼ slices) & slip under the skin on breast & legs.
Squeeze any remaining orange slices into the cavity (to remove juice) & then toss the squished slices in there - including the end pieces.
Add juice to the cavity. (For lemon, I use the frozen Minute Maid lemon juice.)
Cover roaster & roast at at 425 degrees for 20 minutes. Reduce heat to 325 & roasted a couple hours until it is falling off the bones.