Has anybody found a solution to this problem?
Yes: Develop custom firmware.
Perhaps another version of the AT firmware could be written on top of the available tool chain?
You'd only have to flash it once.
Note that the current AT command set isn't that great, because it is very hard to build a correct parser for it, partially because it is poorly documented, and partially because it's not designed for that.
Turning echo off helps, but is not sufficient.