Well, the reason Mechs get used so much, and are so effective, in the Battletech setting is due to three factors that directly counter your approach and fuel the Cult of the Mechwarrior: Force Concentration, Survivability, and the nature of Space Travel.
Simply put, Mechs in Battletech will nearly always give you more bang for your buck than a vehicle of equivalent weight. For example, for 25 tons you could get a Scorpion Light tank with an AC/5 and a Machine Gun...or you could get a Commando with a Medium Laser, a SRM-6 and SRM-4, putting far more damage into the field than the tank (in the PC Game it would be 60 Vs. 105 Damage), while also being a third again as fast as the tank, helping its scout/harasser role. And if things go wrong, they can bug out by running very very fast.
Yes, you can buy 6 Scorpions per 1 Commando, but if you have only enough space to move 20 25 ton warmachines in your spaceship, which are you going to transport? 20 Scorpions or 20 Commandos?
Don't get me wrong here, CAW isn't obsolete in BT, but its use has shifted into defensive purposes due to the existence of Mechs. You want a Mech heavy force to be the ones that attack a planet, because they are the ones that actually stand a chance against the superior number of tonnage the enemy can bring to bear, especially with pre-planned and constructed defenses.
And I am going to keep to that ethos of the series and games for this quest.