OK. So I fiddled around with it a little more to get the configuration below.
Now what I can't figure out is a failover configuration for MMP. Say RouterB is hosting the bundle connection to RouterA. Any traffic going to RouterA is going through RouterB. If RouterB fails, I want RouterC to pick up the connection to RouterA. The only way I can get that to happen is if I disable and reenable the serial interface on RouterC (connected to RouterA).
Also, shouldn't MMP load-balance over both routers?
PS. I'm using HSRP to keep the ping going if I turn one of the routers off.