I think environmental sealing has to be fixed, which means the (C) has to be a variant, not an omni config.
With stealth armor a LVSPL is right out - it would be 19 tons with heat sinks! GR or Arrow IV just barely fits, as long as you give up most of the armor and speed, and don't fix a C3i module.
If you get some clantech weapons, you can get something like this:
Raider
Mass: 30 tons
Tech Base: Inner Sphere
Motive Type: VTOL OmniVehicle
Rules Level: Experimental Tech
Era: Dark Ages
Tech Rating/Era Availability: E/X-X-F
Production Year: 3132
Cost: 3 293 750 C-Bills
Battle Value: 276
Power Plant: 100 Fusion XL Engine
Cruise Speed: 86,4 km/h
Flanking Speed: 129,6 km/h
Armor: Vehicle Stealth Armor
Armament:
15.0 tons of pod space.
Manufacturer:
Primary Factory:
Communications System:
Targeting and Tracking System:
================================================================================
Equipment Type Rating Mass
--------------------------------------------------------------------------------
Internal Structure: Standard 18 points 3,00
Engine: XL Fusion Engine 100 2,50
Cruise MP: 8
Flank MP: 12
Heat Sinks: Single Heat Sink 10 0,00
Control Equipment: 1,50
Lift Equipment: 3,00
Turret: 0,50
Armor: Vehicle Stealth Armor AV - 48 3,00
Armor
Factor
Front 10
Left/Right 10/10
Turret 8
Rear 8
Rotor 2
================================================================================
Equipment Location Heat Spaces Mass
--------------------------------------------------------------------------------
Guardian ECM Suite BD 0 1 1,50
BattleForce Statistics
MV S (+0) M (+2) L (+4) E (+6) Wt. Ov Armor: 2 Points: 3
8 0 0 0 0 1 0 Structure: 1
Special Abilities: OMNI, ECM, STL, ENE
================================================================================
Loadout Name: Prime Cost: 3 828 750
Tech Rating/Era Availability: E/X-X-F BV2: 382
Equipment Type Rating Mass
--------------------------------------------------------------------------------
Heat Sinks: Single Heat Sink 17 7,00
Equipment Location Heat Spaces Mass
--------------------------------------------------------------------------------
Medium VSPL T 7 1 4,00
Guardian ECM Suite BD 0 1 1,50
Infantry Compartment (4.0 tons) BD 0 1 4,00
BattleForce Statistics
MV S (+0) M (+2) L (+4) E (+6) Wt. Ov Armor: 2 Points: 4
8 2 1 0 0 1 0 Structure: 1
Special Abilities: OMNI, ECM, STL, ENE
================================================================================
Loadout Name: A Cost: 4 263 250
Tech Rating/Era Availability: E/X-X-F BV2: 388
Equipment Type Rating Mass
--------------------------------------------------------------------------------
Equipment Location Heat Spaces Mass
--------------------------------------------------------------------------------
(R) Chaff Pod RR 0 1 1,00
2 Anti-Missile Systems T 2 2 1,00
Guardian ECM Suite BD 0 1 1,50
CASE BD - 1 0,50
MASH (7.5 tons) BD 0 1 7,50
Infantry Bay (4.0 tons) BD 0 1 4,00
@Anti-Missile System (12) BD - 0 1,00
BattleForce Statistics
MV S (+0) M (+2) L (+4) E (+6) Wt. Ov Armor: 2 Points: 4
8 0 0 0 0 1 0 Structure: 1
Special Abilities: OMNI, ECM, STL, AMS, CASE, ENE
================================================================================
Loadout Name: B Cost: 4 354 250
Tech Rating/Era Availability: E/X-X-F BV2: 473
Equipment Type Rating Mass
--------------------------------------------------------------------------------
Equipment Location Heat Spaces Mass
--------------------------------------------------------------------------------
2 Anti-Missile Systems T 2 2 1,00
MML-5 T 3 1 3,00
Guardian ECM Suite BD 0 1 1,50
CASE BD - 1 0,50
Drone Control System (7.5 tons) BD 0 1 7,50
@Anti-Missile System (12) BD - 0 1,00
@MML-5 (LRM Smoke) (24) BD - 0 1,00
@MML-5 (SRM Inferno) (20) BD - 0 1,00
BattleForce Statistics
MV S (+0) M (+2) L (+4) E (+6) Wt. Ov Armor: 2 Points: 5
8 1 1 1 0 1 0 Structure: 1
Special Abilities: OMNI, ECM, STL, AMS, CASE
================================================================================
Loadout Name: D Cost: 4 246 250
Tech Rating/Era Availability: X/X-X-X BV2: 1 066
Equipment Type Rating Mass
--------------------------------------------------------------------------------
Equipment Location Heat Spaces Mass
--------------------------------------------------------------------------------
Gauss Rifle FR 1 1 12,00
Rocket Launcher 10 T 3 1 0,50
Guardian ECM Suite BD 0 1 1,50
CASE BD - 1 0,50
@Gauss Rifle (16) BD - 0 2,00
BattleForce Statistics
MV S (+0) M (+2) L (+4) E (+6) Wt. Ov Armor: 2 Points: 11
8 2 2 2 0 1 0 Structure: 1
Special Abilities: OMNI, ECM, STL, CASE