Battery choice is the first thing to look at if this happens to you regularly. Do the research and choose the best battery option for your operation. Battery monitoring systems that will shut down accessories before the voltage gets to a dangerously low level is another option. Optimized idle is an option on most trucks and that will keep the start failure from happening as well. Most APU's have an auto start function that will monitor battery voltage and will start itself if voltage gets to a pre specified level. The APU option works well but it is too expensive to have just for monitoring the batteries, if you have the need of an APU, battery monitoring is probably not an issue.
Another option is an Engine Start Module. This is new technology from Maxwell Technologies that replaces one battery with an ultra capacitor. This module connects between the batteries and the starter. As long as the batteries have enough voltage to start the ECM and energize the starter solenoid the ESM will start the truck.
Since we had the ESM installed, I have noticed the alternator doesn't seem to be working as hard to recover the battery voltage, since there is no start load placed on the batteries themselves. The engine seems to start quicker also, but that may be because the ESM has an 1800 cold cranking amp rating, more power = quicker starts. In theory, the truck batteries should last longer because there will be no extremely heavy loads from the starter.
If this seems like the option for you, check it out at www.maxwell.com/esm. There you will find all the specs, where you can get one, how they work, and frequently asked questions. I would recommend this in combination with an APU for those who have a big power load in the sleeper, computers, phones, TV and other powered items that could run down the batteries.