Cargo Spaceplanes!
How much mass can you deliver to orbit using a Single Stage Spaceplane?
The Rules:
Your craft must take off and land on the KSC runways.
It must return as a reusable spaceplane, which means it can't leave stages/droptanks/etc behind.
Ablative heat shields, and SRBs are considered reusable resources and are acceptable as long as they remain attached.
Use of fairings is also acceptable.
You must deploy your payload in orbit.
Scoring:
I've mostly been building passenger spaceplanes so far. But I do have this I can share, the low tech "cargo" "SSTO" I built for my spaceplanes only playthrough of science/explore.
It uses Swivels and Wheesleys, so only needs "Mun Landing" and "Light Aviation" to build the plane. 205 science total I think. It's so low tech, it was the first vehicle in the playthrough I took into space or orbit. Though the payload shown here was a later one, a Duna/Ike /Eve Flyby Probe, and also needs "Long