You Might be out of luck there. Call one of the smaller places and ask for a “one off” design. Try Tactical Tailor, they Do a closed top design. It says SCAR and M14, but it should work
I use Safariland Kydex. I use them as singles, but they can be attached to each other, and made into doubles.
You can always double up a set of shingles, or HSGI Tacos.