Thanks to all that replied,
I will have a TPMS before our first trip out. The cost of 1 tire is enough to offset the price of one, let alone the cost of trailer damage and down time. We all know a blowout could be sudden and unexpected , but monitoring pressure and temp can make all the difference.
Now which one ? the TST-507RV or the TM-66 M4.
For now I'm only looking to monitor the 5th wheel wheels, I can all ways expand later to the TV.
Update, Just ordered the TST-507rv with the repeater, from good-ole USA with 3yr warranty and 10% off total order w/ free shipping.
Thanks again all,