If you add the oil to the batter it will make a crisper hush puppy.
I would spray with an oil spray just before I put them (1" balls) into a hot oven. Probably 400 for 15-20 mins. I haven't sprayed hush puppies, but I use this method for all my roasted veggies if I want a crisp exterior. (coat with crumbs then spray)
I also spray breaded shrimp and bake it.
"Spray cookie sheet and shrimp with cooking spray, bake in 450 degrees oven, 8-10 min., turn, spray again and bake 8-10 min. more. Watch them carefully!
They came out crispy and delicious! Now that I know how to fix them without deep frying."
I don't see why it wouldn't work with hush puppies.