Hi rbenson ,
Sorry about the delay here. And good discussing with you offline today as well. So likely a good solution here would be to use the BW1099EMB SOM with a custom carrier board, hooked directly to an LTE module.
So in fact, Chris Gammell and Chris Lafky are already working on this design, so you may be able to leverage this effort.
I just pinged them to see if they have any docs they can share on it so far.