My pickup has those, if a tire is low, a light comes on the dashboard and I hear a beep.
The way that works, there is a little gizmo inside the tire, attached to the rim with a thin steel band so it stays in one place, doesn't get beaten banging around in there.
It is the size of half an old time matchbox, very little.
That is a wireless system, so I am sure they can put those on your trailer tires also and you get the signal inside the truck, just as I do with those on the pickup tires.
Works good, mine has indicated low tire twice now and it was low.
DH uses them on his car trailer tires. He's found problems with a tire before things got critical. He also checks tire temperatures with a pyrometer at fuel stops. I will ask him for particulars when he gets home this evening.
I think a walkabout with a pyrometer and hammer might make more sense. Pyrometer is $30, hammer is free.
I daresay that relying on the TPMS to catch a problem condition (because it can detect low pressure sooner), makes it easy to overlook other more dangerous tire conditions.
While that is right, you still always have to walk around and check all before taking off, the indicator that said "low tire pressure" was right, but you could not tell which tire, they all looked the same.
I had to get the gauge out and check them all to see which one and that no other were low.
I think that gadget has it's place, but definitely is not to be depended on only, you sill need to check visually.
Then, when you are driving down the road, you may not know until something is really wrong and that gizmo can warn you before that, like the one big nail hole I had, that I could stop in time, before the tire was too low and made driving dangerous.