I did a fair amount of digging at one point because I was interested in a security system (I was looking for remote camera monitoring but still applicable.)
As Dave(Magicbus) pointed out, the un-obvious thing in these systems is that if you want real-time monitoring/alerts, some sort of connectivity is required. Usually Internet, or sometimes cell like the MarCELL system.
So now you have to look at what sort of customer-supplied infrastructure you can set up. Few of these systems connect directly to the Internet but rely on an existing connection. Campground wifi may or may not exist (or be reliable.) If so, means probably setting up your own wifi router to connect to it. When it's not there, you are probably looking at Internet through a cell connection. Now you are needing some sort of cell/wifi hotspot.
Of course, now you need to be in an area where you have a good cell signal. Usually there, but I've certainly been in campgrounds (Michigan UP) where none exists.
Finally, power. All these things require power, and if you want to be alerted when the power goes out.... hmmm. Now have to figure a way to run both the monitor system and wifi/cell off battery.
All are solvable problems, but not always obvious. Few are just plug-and-play. Most of these systems are designed by someone in an office with reliable power and high-speed Internet with little consideration of being out in the boonies or dry camping in the middle of the wilderness.
Just be sure to dig into which system you are considering and understand HOW it sends alerts to your phone and what's required.
2004 Winnebago Vectra 40KD
Roadmaster Tow Dolly