this is what i mean. of the official LAM designs, there are only three variants* out of 22 total variants** mount bomb bays allowing them to carry additional fuel, and none of them use liquid storage systems/fuel tanks to expand on that internal fuel.
*the WSP-100 WSP-100 Wasp LAM Mk I, the WOB WSP-110 Wasp LAM (which both mount 5 tons bays) and the Pwwka with a single ton bay. the Wasp LAM variants are clearly indicated in the descriptions as usign their bays for munitions, so the only one which seems to have mounted a bomb bay for fuel carriage is the Pwwka.. which could only add an extra 40pts of fuel.
**which includes the experimental Screamer and Shadow Hawk LAMs, and the non-functional Champion and Scorpion LAMs.
Part of the issue is part of the vocal community doesn't like LAMs for reasons of anything from "They break my suspension of belief" (ironic since 'Mechs in this setting are pretty much impossible given the laws of physics), to "They no longer fit the setting" (which is understandable, since BT is no longer an Anime sim), to "they are the cheesiest cheese that ever cheesed even if you put them on a cheeseboard and compared them to cheese" (parts of them were under some rules, some of which was from creatively interpreted rules) and all this resulted in a rules rewrite to them that some would say nerfed them rules wise, which results in LAMs that are a dead end tech by design, and thus any LAMs we see will have obvious flaws, such as no extra fuel, limited weaponry, ect
That being said i think they were over nurfed and while they can be the purest of cheese in pick up games, they would become balanced in large, long term campaigns where you have to deal with crew training times (it takes longer to train a LAM pilot than any other crew afaik and then that leaves you with a pilot that's less proficient than either a 'Mech or Aero pilot), funding units, Logistics, strategy and tactics, where the costs and times needed would balance out the LAMs strengths, but those types of game are rarer than LAMs in 3153 and i don't think there's even rules to cover things like training times or tax bases...
TLDR: LAMs have limited tech to use in them, something had to be sacrificed, that something was fuel because pick up games are the rule and they had to be somewhat usable at least in a pick up game so they went weapons and armour in the designs and sometimes a dash of "what chemical was the in universe designer using to distract themselves while designing it"
