Feasibility of a MKR GSM 1400 to operate a linear actuator, remotely

I am considering buying a ABX00018-B to implement a project that requires the actuation of a small linear actuator that will pull a pin on a drop gate at a remote location when an SMS keyword is received, then confirm receipt/action of the command. I have planned on using a LiPo to power the unit, but a 12V lead acid battery will be in the vicinity for when the actuator needs to turn, so I guess stepping that down is an option.

I have some general concerns that likely stem from my inexperience in this realm:

  • overall impression of the MKR GSM 1400? is there a cheaper alternative?

  • the datasheet for this board states 7mA per output channel. Can this be combined with 2 or 3 channels firing at once if the typical coil current of my external relay is 10mA? I am assuming a DIN rail mount 3A relay right now, which may be a mistake (CN024D05). I assume most of you use much smaller PCB-mount components. Right now I am trying to avoid breadboards, if possible, due to the environment.

  • the 2dB antenna. This location will be fairly remote but cell phones do get service typically. Do users of this board with similar applications often find themselves utilizing an external antenna via the micro UFL connection? I'm envisioning a microstrip antenna of a cell phone and assuming that's roughly 6dB at least, so will probably be looking to upgrade. Any recommendations?