has anybody tried these products before

Never considered that (IR). I have a HF one, think it was about 20 bucks.

You might also consider a IR thermometer gun. They are cheap and will work on your tanks if you are using propane at the time which creates a difference in temp between the liquid and gas portions of the tank. They are also handy to check things like specific engine component temps, tires, brakes, BBQ grill :)

They vary in price but even a cheap 20 dollar unit will be plenty accurate to check your propane tank levels and a bunch of other stuff.

IR Thermometer.

I have the tank Monitors. They work well.

tank monitors on another forum

I have both of the items mentioned.

I like the WiFi Ranger as it significantly extends the range of my connections and gives a stronger signal to the closer ones. No issues, nice having a secure network for my internal devices (WiFi printer, for example).

The sensor works as described, I mounted the display along with my other sensors. Only downside is the battery does not seem to last as long as I would like, had it just over a year and replaced twice in one sensor and once in the other. Not a big issue, however. Easy to change.

MN Ben wrote:

https://youtu.be/d3DE_IDOOrs

Informative video, but the second video doesn't describe an "issue" persay, it's an "operational characteristic" in my book.

The inside monitor is calibrated for 20 lb tanks.
You can buy the system with just the sensors, and use the bluetooth to a tablet or smart phone. The app gives you the ability to set your tank size.

I bought the Dometic after I ran out in my Wolf Creek and I lost contents of refreg.

The Dometic checker works great. But you need to put one hand on top of tank, then press checker against tank with other hand to have it work perfect.

I was interested in the LP Tank Monitor so I did a little research which brought me to a couple of informative youtube videos. The first is the original setup/use of the product and the second is a follow up on the product which revealed an issue. Also in the second video is another LP measurements tool by Dometic.
https://youtu.be/4PTJ1KajJrc
https://youtu.be/d3DE_IDOOrs
Ben

WifiRanger is a good product, but expensive due to the integration software. If you are technical, you can do this for less money. If you are not, it may be money well spent to avoid frustration.

I use a Truma propane monitor, works really well. Handheld, about the size of a mini-Maglite.