My XS-Rib was fitted with pressure relief valves, as it get toasty quite often over here in Sunny California.
Only problem is, they do their job and vent off excess,but then when it cools down at night ,the tubes tend to get the "floppies".
So its usually a little top up next morning before it heats up,just so its not flopping around on the trailer.
3.5psi seems good
Luckily had an old low pressure /high volume spray unit that puts out about 10 psi. So I made up an angled inflator adapter from some PVC , to go on the end of the spray hose , which is great for quickly topping up the tubes before leaving home.