So the new sub-mod update gives us a major expansion that can be built off of. This is great the OP now has more to work with and a decent amount of work completed for them.
So what more do people think should be added? The logistic support part of the fleet could use some expansion aside from just the Charon.
A frigate-scale cargo ship would be something like the
https://www.halopedia.org/Brahman_light_haulerA ship I say can be added would be the
https://www.halopedia.org/Mariner-class_transport_ship like the Ace of Spades just without the Forerunner upgraded systems. I think it is meant to be a post-war design but could be a late-war design like the Strident as well. Make it a destroyer-scale logistics ship to be better than the Charon without a MAC or ground support package.
The
https://www.halopedia.org/Bustler-class_freighter could be another destroyer-scale ship focused on salvage and repair/refit instead of pure cargo focus. Not sure if there is a hull mod to affect the repair/CR recovery of the fleet instead of just on itself. If not hopefully someone knows how to make one.
For Cruiser-scale cargo ships, the
https://www.halopedia.org/Mulzac-class_transport would work best. Make it faster than the Colossus with similar if slightly altered cargo space. Lightly armed like any other cruiser cargo ship its size.
Capital scale cargo/salvage/repair is covered by a Phoenix Class Colony Ship. The "Civilian" version would be a mix of the base game Atlas and a larger Skyliner. Just with maybe 20 percent less cargo space, about 3000-4000 crew space, and a decent but not huge fuel tank. Give it the Salvage gantry and Survey Sensors, or a modified version like what the Roider Union Argos Class has if that fits better.
The military version would be a cargo, fuel, and crew scaled-down version. With more armor, hull, and uprated flux stats/UNSC militarized subsystems. Add in an advanced ground support package. Cruiser-level weapons load out at best but lean more toward a heavy destroyer level. To show its passable defenses but still under-armed for a ship its size normally would be.
For transport ships of crew, there are enough options for frigates, destroyers, and cruiser-sized ships. A small transport like the
https://www.halopedia.org/Vancouver-class_courier about the same crew level as a Mudskipper should fit it well.
For Destroyer-scale transport there is an option for civilian and military/ground support ships. Either the
https://www.halopedia.org/Banta-class_colony_ship or the
https://www.halopedia.org/Egret_Spaceliner with the one not chosen for the crew becoming the UNSC version of the Valkyrie instead.
For a cruiser-scale transport ship the
https://www.halopedia.org/Star_Charter-class_colony_support_ship works best. It is meant to be part of a Pheonix led colony fleet so being a Cruiser to the Phoenixe's Capital-sized transport. Crew capacity on the same level as the base game Skyliner.
No need for another capital scale transport with the Pheonix already listed.
For fuel there aren't too many good choices that have pictures. Maybe the
https://www.halopedia.org/Ibis-class_freighter,
https://www.halopedia.org/Parabola-class_freighter, and a modified version of the prison ships designed for fuel
https://www.halopedia.org/Mona_Lisa for frigate, destroyer, and cruiser respectively.
For Capital scale fuel transport the
https://www.halopedia.org/Springhill-class_mining_ship with its huge container silos looks good as a fuel tanker.