I wouldn't bother using a smart plug. The other thing that's real dangerous about them that I didn't really elaborate on is the relay. There's a reason on something like a pump, fridge, AC unit, etc. you'd see a real contactor instead of a relay, and it's because relays are inappropriate and have dangerous failure modes for big loads like that and are typically way too small.
In most real non-resi situations, you'd probably isolate the hot leg and put a good CT (current clamp) on it and read that. The great thing about that is you haven't added anything in the power path for the device, like a shunt which is what most smart plugs use. Current clamps are good for a lot more current (though I guess a proper shunt could do it too). The easiest way to do this in your setting is to find a good UL-listed electrical box with cable glands, a short piece of DIN rail, a male and female plug pigtail, some proper THHN wire and wirenets and a Shelly 50A EM Pro, and just graft the EM Pro into the box and wire it up with it's CT. You've now got something signficantly more durable and probably safer (and correctly specced for the load). I've done other things like using an HV Labjack and some good CTs or other one or few off designs. There's lots of stuff in the commercial/industrial space that does this well but it tends to be $$$. Again, for the sake of my own family, I wouldn't use non-UL stuff (most plugs and things that go in gangboxes that are "smart" aren't UL listed, and MAYBE are ETL) as you who knows how much or how well it's tested.
In most real non-resi situations, you'd probably isolate the hot leg and put a good CT (current clamp) on it and read that. The great thing about that is you haven't added anything in the power path for the device, like a shunt which is what most smart plugs use. Current clamps are good for a lot more current (though I guess a proper shunt could do it too). The easiest way to do this in your setting is to find a good UL-listed electrical box with cable glands, a short piece of DIN rail, a male and female plug pigtail, some proper THHN wire and wirenets and a Shelly 50A EM Pro, and just graft the EM Pro into the box and wire it up with it's CT. You've now got something signficantly more durable and probably safer (and correctly specced for the load). I've done other things like using an HV Labjack and some good CTs or other one or few off designs. There's lots of stuff in the commercial/industrial space that does this well but it tends to be $$$. Again, for the sake of my own family, I wouldn't use non-UL stuff (most plugs and things that go in gangboxes that are "smart" aren't UL listed, and MAYBE are ETL) as you who knows how much or how well it's tested.