These might save the day
(Save me like $150)
Less cheesy T5 fittings for an upgrade.
The listing for the fixture up above says they use BallastWise ballast, so the fixture might have an instant start ballast. If the existing tombstones only have 1 wire to each, that means they're shunted. You'll have to make a splice and take a wire to both sides of the non-shunted tombstones.