One of the good things about garter belts and stockings in the bedroom is easy access without having remove the stockings.
I usually wear either NO underwear or side tie panties or crotchless panties under my garter belt if we're going to be playing soon. If I am just wearing a garter belt and stocking to a regular even and don't want to wear side tie panties, I'll wear them under the belt. Then I rush to take them off when we get home. So, I usually use side tie panties. You wear these UNDER the garter belt but they are so easy to take off and not disturb the garter belt and stockings.
These are panties that have little ribbons on the side which hold them together, you put them on and tie on each hip and you or your lover unties them and they fall off, leaving the garter belt and stockings intact. I got a nice supply of these brand new on EBay a while ago. (And washed them
well when I got them. They were stiff at first and had tags on them and IN them, so I know they were new. Plus, I use this seller for stockings and panties so I know she is trustworthy.) Eden sells crotchless panties, which I also use. But, Eden does not sell a lot of side tie panties. I wish they would. I think the Rumba Panties with bra are side tie.
Here's a pair.