Space is another issue here. Two MMP's would take up too much real estate in an already strapped crawler. The thing is that the motor current in crawlers is relatively low compared to what people put monster trucks, buggies, and truggies through. I would have to believe that the BEC issue has to do with the fact that many people use the strongest servos they can and you get a lot of stall current (maybe incorrect term) when up against rocks and trying to turn.
Like Arct1k said maybe a jaunt over to
www.rccrawler.com and ask for input would be helpful. Many over there already support CC so you wouldn't be going into the lion's den so to speak.
Honestly you may could get away with a dual Micro Mamba setup with a shared brain. I really don't think the systems would require more peak amps than what it provides. Seeing as most people in the crawler world run 55t motors as the standard you can see what I mean.