something like an Gargoyle/Man-o-war would be useful for proto-delivery.. at 80 tons it could carry up to an 11 ton proto without hinderence, and the 5/8 speed would be useful. the Executioner, with its 4/6[8] movement profile at 95 tons, would also be pretty good, able to carry nearly any MCS equipped proto without losing speed.
and i just realized that with the Omni discount, a Fire Moth could carry a Roc Z... >:D