Well, BlackVue doesn't say they support hardwiring... but BBMC suggests you could purchase a Cigarette Socket Hardwire Kit that would work with the B-112.
So in theory, yeah. I haven't seen any evidence of someone actually doing it though, so take that with a grain of salt.
If you already have the cellink installed; it may be better to get a portable power bank dedicated to your hotspot.
Next step would be ensuring the combo keeps your hotspot on (some hotspots turn off/go into sleep mode due to inactivity, may want to take a look at your settings if you haven't already).