Okay, so according to Tactical Ops chemical lasers don't cause heat in conventional fighters, combat vehicles or ProtoMechs (TacOps p319). Interestingly they can be used as handheld weapons for BattleMechs and don't build up heat there either. I have the mental image of Phoenix Hawk replacing its large laser with a hand-held pod with four medium chem lasers with a ton of ammo - that's only 30 shots split among four weapons, but it would really be useful for close-range firepower applications like battle armour hunting.
Anyway, onto the vehicles. My usual disclaimer applies - if I try to use the code template to create a datasheet it just looks awful, so I'm just going to write my ideas as text. Here we go...
TRO 3039
* Ferret VTOL - replace MG and ammo with Medium Chem Laser, replace Infantry Bay with 1 ton MCL ammo.
A very fast but fragile harasser.
* Wheeled APC - replace 2 MGs with 1 Medium Chem Laser, replace 1 ton MG ammo with 1 ton Medium Chem Laser ammo.
Provides some level of direct fire support for infantry against light vehicles and fortifications
* Skulker Wheeled Scout Tank - replace medium laser with Medium Chem Laser, replace 2 heat sinks with 2 tons MCL ammo, replace 1 heat sink, power amplifier and cargo with 1.5 tons cargo space
A scout vehicle with enough cargo space for provisions for a long-range mission, or possibly be refitted to carry a squad of infantry or scouts. When the post-Helm Core tech boom hits, the space is exactly the weight for a Beagle probe or Guardian ECM.
* J Edgar Hovertank - replace 145 fusion engine with 145 fuel cell engine or 95 ICE engine (fluff text in TRO 3039's entry for the J. Edgar mentions that fusion engines became more difficult to acquire for vehicles), freeing up 1.5 tons of weight. Replace medium laser with Medium Chem Laser, use spare 1.5 tons from engine replacement to add 1 ton MCL ammo, remaining 0.5 ton can be used for additional armour or cargo/personal gear.
* Scorpion Light Tank - replace AC/5 with Large Chemical Laser and 3 tons ammo, replace AC/5 ammo with 1 ton armour. Lighter weapon reduces turret wt by 0.5 tons, add 1 MG to front.
Scorpion Light Tank Urban Warfare - replace AC/5 with 3 Medium Chemical Lasers, 3 tons MCL ammo, 1 ton extra armour and 2 MGs. Lighter weapon load reduces turret wt by 0.5 tons, add 1 MG to front. Replace AC/5 ammo with infantry squad bay.
Total loadout - 3 medium chem lasers (30 shots each), 4 machine guns, 1 infantry squad
*Pegasus Scout Hovertank - replace medium laser with Medium Chem Laser, replace 2 heat sinks with 2 tons MCL ammo. Replace 1 heat sink, power amplifier and cargo with 1.5 tons cargo
* Saladin Assault Hovertank - replace AC/20 and 3 tons ammo with 10 forward-facing Medium Chem Lasers, 5 tons MCL ammo (15 shots per weapon) and 2 tons additional armour.
* Scimitar Medium Hovertank - replace AC/5 with Large Chem Laser and 3 tons LCL ammo, replace 1 ton AC/5 ammo with 1 ton SRM ammo.
* Hetzer Wheeled Assault Gun - replace AC/20 and 4 tons ammo with 12 forward-facing Medium Chem Lasers and 6 tons MCL ammo.