Another issue would be modeling MASC's tonnage and crit requirements.
In BattleTech, IS-built MASC takes up a number of tons & a number of criticals (that all have to be in the same place) equal to a 'Mech's total tonnage divided by 20 (rounded up to the nearest integer for both tonnage and crits), while Clan-built MASC takes up a number of tons & a number of criticals (again, that all have to be in the same place) equal to a 'Mech's tonnage divided by 25 (rounded up to the nearest integer for both tonnage and crits).
As such:
- a MASC system for a 20-ton IS 'Mech would weigh 1.0 tons and consume one critical & a MASC system for a 20-ton Clan 'Mech would weigh 1.0 tons and consume one critical,
- a MASC system for a 45-ton IS 'Mech would weigh 3.0 tons and consume three criticals & a MASC system for a 45-ton Clan 'Mech would weigh 2.0 tons and consume two criticals, and
- a MASC system for a 100-ton IS 'Mech would weigh 5.0 tons and consume five criticals & a MASC system for a 100-ton Clan 'Mech would weigh 4.0 tons and consume four criticals.
There may also be the issues of whether MASC should be available to all 'Mechs or restricted to specific variants (thus giving incentives to playing those specific 'Mechs/variants), and whether MASC can be mounted anywhere that there is space (like BAP) or if there would be a specific "MASC hardpoint" (as there are specific hardpoints for both AMS and ECM), how to make not equipping MASC an option comparable in potential value to equipping MASC (that is, how to make it so that MASC does not become a "must have in order to be competitive" item), (if cross-tech customization in general is allowed) how to deal with cross-tech MASC compatibility as well as cross-tech MASC comparability/balancing (e.g. what additional drawbacks (if any) would/should Clan-built MASC have in exchange for being lighter and smaller, in order for IS-built MASC to remain worthwhile as a potential option).