Reddog1 wrote:
. . . How do we pick and choose what part of the decal we ignore?
This appears to be the heart of your question.
My answer would be: It's better to NOT ignore the decal specifications if one does not understand it's purpose and it's limits.
Airing down tires for beach sand is an example. It's done to meet conditions.
Obviously, airing down is an extreme example, but one could stick to the decal specs and it would not hurt the truck. (Other than getting stuck.)
I find it interesting that the dealer service adviser did not follow the decal specs. Dealer service advisers, in my experience, will only quote the company specs.
When it comes to getting non-company advice, I have to ask the service adviser what other owners are doing, their experience and the adviser's opinion of their experience.
The original poster made a step in the right direction in his attempt to learn something about tire pressure through the experience of others.
Hopefully, he will do further research outside of this forum and integrate that research with the opinions and experiences provide here.