Since my truck has its own built-in tire sensors I just have wireless ones for the 4 trailer tires. I think the trailer TPMS is more important as it's hard to feel anything when things go bad versus the truck. Also, I feel the trailer bearings or brakes are more likely to fail and cause an overheating condition than my truck. But, if you have the extra money it doesn't hurt to add sensors on the truck as well.

I had factory vehicle and TPMS on my RV in the past and currently have the integrated system with my 2020 GMC. Both are very accurate compared to my tire pressure gauge and can easy see tire pressure variances while towing. You can see the difference in pressures based on sunshine and wind direction. Our main focus is tire pressure and temperature on our camper and have caught a potential tire failure as we had one tire fall several pounds below the tire on the same side. We were able to stop at the next town before the pressure got to low and we had a nail in the tire. If I didn't already have tire pressure sensors on my TV I would add sensors.

It's always seemed to me - speaking not from experience, mind you - that the TPMS system I add to our 5700# trailer come with an app so temps and alarms can be displayed on the mounted cell phone in our TV cockpit. This assumes the phone is mounted prominently and alarm settings can be suitably set. Being crafty and talented, I know Ray prefers a bountiful collection of independent displays & cameras in his TV cockpit, and they are probably each more 'prominent', being bigger. But instrument flying has shown me that a simplified scan while 'driving' seems to be a much safer choice. Still, this is just me trying to reason out the best display option. I'd welcome hearing challenges and comments about my thinking from you folks before I purchase and install my system of choice. Thanks!

Has anyone used the TMS sensors that go inside the tire, instead of the externally-mounted versions ?
In reading about the external types, I am quite nervous about shortcomings expressed by experienced RV users.
Any thoughts ? Anyone in LYRV-land who has tried both, or gone straight to the internal type ?

My 2016 Ram 3500 didn't have a sensor for the spare, so I bought one when I got my system for my fifth wheel. I also installed a sensor on the spare for the fifth wheel. (Ours are external, and I moved them from my 2015 bumper pull and have never had an issue.)

FWIW: My Ram's sensors only monitor pressure and do not alarm for low or zero pressure situations. We drove a long way (100+ miles) with one of our dually's down while towing our car hauler. I just happened to check the tire pressure on the truck and saw pressure in one of the inside dually's was zero.

A few hundred miles earlier we were going over some very rough interstate in Illinois and didn't realize we hit something in the road and lost the tire.