I looked into the Draftmaster. I love the design.
I think a good fabricator could make a triplet work on a Draftmaster. Add an extension and some additional bracing.
Here is what Draftmaster told me:
The longest Specialty Rail we make for the Draftmaster fits wheelbases up to
84 inches. We don't make a Draftmaster attachment for triplet tandems
because we feel the triplet would stick up to high and cause too many
clearance and loading issues. However, we do make a stock model of our
Tandem Topper roof mounts for triplets. It's the TT-321, so named because it
can carry a triple, double, or single bike.
Charlie Bxxxxxxx
Atoc Inc.
www.Atoc.com
www.TopperRacks.com
www.Draftmaster.com