Alternatives to a strap?

I need a strap for my metal cage. It doesn’t bug me during the day, but I’ve now had about 3 nights where it becomes uncomfortable due to erections and everything says get a strap to hold it down. But my KH/Wife is very germ focused and wants something that can be washed/changed daily (like underwear). Short of getting seven straps and doing laundry, does anyone have any suggestions on something that would help.

I have tried tighter boxer briefs, but that didn’t fix it one of the nights..