Yes, you can absolutely pull this from the API. See here. It gives you csq value for that connection, so long as your modem supports it.
What model cellular modem are you guys are using? We've got a good assortment of MiFi 620L's & Pantech UML290's from Verizon. The 620's unfortunately don't let us see signal strength, but the 290's seem to show 5 bars no matter what the strength may actually be.