This is brushless forum, so you should check out some outrunner motors for your maxxcrawler
Holmes Hobbies Crawlmaster 3014 seems very interesting and is specially made for sensorless crawling. You can also try some bigger motors, like 3020, 3026 or even amazing 3032 :) These motors run smooth enough for crawling.
You have excess of energy and MM ESC. That obliges you to do this
> HB L2PE + MMM + Medusa 60-1600 @ 6S A123
> HB LSP + MMM + Medusa 70-1600 @ 6S2P A123
> AE B44 + MM + Medusa 50-3300 @ 4S A123
> AE J82 + SW 5700 @ 2S LiPo
> AE TC5R + MM 6900 @ 2S LiPo