Is it possible to use cargo space in BattleMechs and IndustrialMechs to carry conventional infantry and Battle Armor?
I understand it is possible to have cargo space and IndustrialMechs are clearly mentioned but the rules does not mention how to load/unload infantry
There aren't any legal rules but there is fluff about it happening. The Firemoth/Dasher was originally designed to carry infantry on the underside of it's arms but the idea was abandoned after it was insulted. Also the Daedalus's fluff said it carried live cargo. That could be animals, plants, or people.
The Harvester Tripod from War of the Tripods carried battle armor and deployed them with lift hoists. I think they're more canon rumor than canon. Nebula California also gives rules allowing the Star Empire to put infantry bays on Mechs but it's not canon.
As to how they would load and unload, boarding ladders or tubes. Like at the airport. Folding stairs, ladders or just climbing ropes/ziplines, and the lift hoist as used by the Harvester Tripod. I suppose the mech could also go hull down and allow troopers to just climb in. They could also be carried in a cargo container. That'd probably be easiest for motorized/Mechanized infantry. I would think you'd need a bigger mech with lift hoists for that though or risk injury. If the infantry/BA can jump of use VTOL movement I'd just they could just jump out.
All the above would be illegal outside Nebula California, War of the Tripods, and your table (and mine :thumbsup:) so don't forget to give those mechs the Illegal Quirk if the GM allows them.