I *love* Classic Battletech -- 3025. Love it.
I've run a couple of campaigns, and I've played a mechwarrior in three campaigns, using just the Classic Battletech material (box set, 3025 Readout) -- no Mechwarrior RPG stuff. The PCs had names and backgrounds, but the only stats were piloting and gunnery. We never played anything outside the mech combat where we needed character stats.
I usually just managed the campaign stuff in a general way. Mechwarriors gained skill by surviving battles, (not necessarily winning the battles). One campaign in which I was a player, as a mechwarrior, the GM used all kinds of campaign books and he and the commander PC tracked money, parts, costs, etc. in detail. This was way, way, way more complicated than I'd ever want to do.
I really like the idea of each player is an individual warrior with his personal mech which he brings to each battle. If they capture an enemy mech, they can cannibalize for parts or even upgrade to the new machine. It's pretty cool to be able to upgrade from a medium to a heavy mech after "serving the time" in the medium.
As a Player, in three campaigns, I have fond memories of my personal mechs: an Archer, an Enforcer, and an Orion. There is a thrill in campaign play with painting kill markers on your mech, and a panic when you have to go into the next battle with lingering battle damage from the previous.
And though it's not common, sometimes a mechwarrior dies -- my Orion driver took a hit in the cockpit, and died.
I wholeheartedly support campaign play in Classic Battletech, without any of the actual campaign rules.
Bullgrit