That's what I thought about my last trailer with the Cat's Eye indicator. I just made sure the Eye was closed and took off. After I blew a tire I looked and what I thought were pressure indicators were simply fancy valve stem covers. Checked and they are all low. 4 new tires later I checked every time we left out and still worried about it.
On the new one I added the TPMS and love it. When we are getting ready to leave I turn on the monitor, give it 5 minutes and then see if I need to add air anywhere...
Clif and Millie
Ozzie (half a dog tall & 2 dogs long)
2009 Ford Lariat F350 SRW CC Diesel
2013 Cruiser CF305SK Patriot Edition