The manta's cargo hold can be outfitted to hold whatever the mission requires. The commonly displayed loadout contains what most commanders prefer, but they can be tailored to what a commander wants. So instead of hammerheads maybe a store for broadsides. As far as rapid deployment of broadsides they could be dropped like other battlesuits and equiped with one time use retrorockets to slow their decent.
That said i kinda like the idea of the converted bomber... would look rad.
While the ficiton holds up that XV suits get Manta/Orca dropped - don't let that hold you from a modified Bomber dropship! I think its a wild idea and has the right layout already for a very unique take