I'm not sure anyone can say that a nail won't go through a LT tire just as easily as it would a ST tire. I have had several flats with $500 ea tires and it was just as easy to get as the flat I recently had on my ST trailer tire. There are also road hazards such as large chunks of metal that will lay waste to any tire if you don't see it in time.
If you are up for it, take the gamble. I just think any argument against getting a TPMS is incredibly strange. Even cost is something that shouldn't be under consideration. If you can afford a trailer, you can afford to tow it safely or you really can't afford a trailer.
TV: 2012 Ford F350 CC 6.7L 4x4
TT: 2014 Wind River 250RDSW [Dual Crown 6v, Trimetric, Iota 15.4v 55A charger]