I've used all metal kabob skewers (No plastic or wood handles here please).
Use 3 of them. Stand a rib rack on its edge and shove a skewer through between the bones on each end. Leave at least 2 bones outside the skewer so the y don't tear out. Poke third skewer through the middle. Take another rack of ribs and thread it onto the 3 skewers leaving an inch between it and the first rack. Repeat till your skewers are full.
I've done this on a large grill (55 gal. drum) and it works great. Got 20 racks on at a time.
4 times 5.
The only limitation is the length of your skewers and how much meat you can lift at a time.
Alot easier to clean than a standard rack as well.