I've been using Craggy's 500107 on the glare shield, and no B antenna.

1/4 wave antenna high performance with a slim profile. It operates at 916MHz. The overall antenna length is 2 7/8-inches (73mm). It features a bulkhead mount, flexible whip and, cable to PowerFlarm A or B with 4" square ground plane.

Looks much less ghastly than the dipole antenna and works very well.
Installed with ground plane velcroed to the underside so it's easy to remove the canopy or tear away if needed.
5Z and I checked range last Sunday, were fine with both our installs.
ADS-B reception is fine with the stock dipole antenna below the glare shield.
Personally don't care to see or hear about Mode C.
Jim