Need a new cover to fit over XL workhorse

[armywife21]

I need a new/some new covers to fit over my XL workhorses that I got and LOVE! The Only problem is my son doesn't have a huge waist so I don't want the cover falling off of him but I need a long enough rize to cover everything. Our size 2 capris and flips work but the green kind of sticks out a bit and I'm worried if it was wet he would in turn get everything else wet too. I am open to anything cute. No ugly covers though.