Does anyone use stabilizers under their slide out?

No they are not required.

Some use scissor jacks under the trailer frame. You can buy them at a junkyard for about $10. Look for ones with a 3/4" nut to raise and lower them, then get a cordless drill, and use that to put them up and down. This will keep the trailer from swaying side to side.

Trailer leveling systems are a pair of scissor jacks mounted to a frame, with quick turning handle to deploy them and retract quickly, but the drill is much faster.. .

Fred.

I don't use them!