I run around 45 psi (somethimes a little more depending on my load) on the pavement and down to as low as 20 psi in the dirt/sand.
When I was working (yuck) we did a LOT of research with all the major tire companies about reduced tire pressure (RTP). This was for log trucks and belly dumps hauling on dirt roads. We wanted to keep 'em off the roads till late spring, or until all the moisture was gone, as the higher tire pressure was really rutting the roads and causing greatly increased road maintenance. All the tire manufactures said the only problem with RTP was driving too fast and having heat buildup due to increased sidewall flexing. We found that with a serious buldge in the sidewalls the roads were actually in better shape, the truck drivers were super happy 'cause of the better ride and they weren't getting insignificant heat buildup at speeds up to 40 mph.
I have found that the best way to go is to reduce pressure till you're happy with the ride and then get out every few miles and check the sidewall temps with your hand. Very warm is OK. If it's hot, ya need to slow down or add air.
Here are some shots of my tires.
This is my Toyota truck tire at 10 psi that I use here in Baja for all my running around.
This is my SMB tire from the rear at 21 psi.
The SMB tire from the side, again at 21 psi.
I really don't use a tire gage when I'm reducing my tire pressure, I go by the bulge in the tire which is what gives me a bigger foot print and a softer ride. The tire pressure will be different for every tire and rim combination and for the load the tire is carrying. With this amount of bulge, I keep speeds below 40 mph and never get any significant heat buildup. I know it's possible to roll a tire off a rim or break a bead, but in over 35 years of doing this I've never had that happen.
This is just what I do and what works for me (and lots of other guys that I run the dirt with). Everyone needs to do what works best for them and what they are comfortable with. Experiment when you're out running around and see what works for you.
The biggest problem with RTP and a big bulge in your tire is that the sidewalls are much more exposed to sharp rocks and cactus. Sidewalls are the weakest part of the tire so....
Anyway my two cents worth.
Just do something, even if it's wrong.