Blanket??

Please don’t judge I’m just looking for options... so we struggle to regulate the temperature in LO’s room. It’s still hot when he goes to bed even with AC and ceiling fan but as it cools outside his room cools off and it gets chilly in the middle of the night. He won’t sleep in pants and long sleeves because it’s too hot for him at bedtime and I’m worried he’s getting cold at night (he’s been stirring a lot) has anyone used a blanket with their LO’s yet? I’m tempted to sneak in when I turn off his fan and place a blanket on him... but im also worried because I know they don’t recommend anything in the crib...