Seeing how a cERLL is 248BV by itself and 4 LRM-5s w/ 1 ton of ammo is 227 BV, that would be something. One might even say impossible.
Edit: Even with an ultra-light, slow fusion-engine wheeled vehicle with a cERLL with minimal armor I still get ~350 BV You basically have to artificially remove armor and keep the vehicle slow to get it near 300 BV.
Oh You mean Glass Cannon units like several different kinds of Missile Carriers, LRM-Flatbed Truck, and numerous others units?
Ive been making it clear since page 2 of this thread that Ive been working for making them using various tools. Battle Armor were one possibility under the reasoning that if you could get 4-6 BAs per hex with LRM-5s you could get the equivalent of an LRM-20 for much cheaper than a battlemech. Not really working because I dont have the rules so I dont know if you can have half a ton of ammo on a 2ton Battle Armor.
the Flatbed-LRM truck is one option. Its under 200 BV and 5/8 movement isnt bad. Its quite cheap, but even then maybe split it in half to have 2 LRM-5 trucks.
LRM Missile Carrier is another. Its speed it slower and continues to half almost no armor. Its greatest flaw is that its about 900 BV and it could be destroy in one lucky hit. So have about fractioning that? 6-12 separate units would be much more resilient.
The problem with glass units isnt that they have low defense, but rather they dont exploit that. Many do as having high speed makes you hard to hit, but also raises the cost alot. These ones dont have Vehicular stealth armor...or just divide them.
Custom Scout units are not really necessary. There are plenty already. Swiftwind, Ferret, The Sprint even has official C3 versions. Add some Stealth armor, maybe.
Not Frontline "tank" units are harder as the obvious problem is you can just ignore them. If they have massive armor and low weapons you can just skip to the nice glass cannons. In Theory you could make something with Hardened Armor at a relatively cheap cost. Maybe make it fast and use it to ram.