My problem is that what I really want from a Battletech RPG is a seamless merging with the Battletech miniatures game. I want roleplaying rules that let me use the miniatures game for combat resolution, and which help me structure a game around the things I love most about the Battletech universe- campaigns and salvage and mech upgrades and mech on mech violence.
This would probably require some adjustments of the Battletech rules, to get rid of some of the easier, completely random mechwarrior deaths. Its bad enough when your Warhammer walks onto the field for the first time and immediately takes a PPC shot right to the face that criticals into the cockpit, but its even worse when that was your PC inside.
I doubt that there is a way to seamlessly merge the RPG and tabletop games. The 'mech combat is just too deadly on the character scale. You are going to have to accept that occasionally someone is going to suck an AC/20 to the head.
I have always had the view that with Battletech, death is a fact that all mechwarriors have to live with. Someone is eventually going to have their character killed. That should be understood from day one.
On the onter hand, if you are playing Battletech as part of an RPG, it seems to me that the simplest fix is to simple turn the AC/20 hit from head to CT, and turn the occasional cockpit crit to a sensors hit. It worked for me pretty good.