First, caster is what contributes to straight line stability, so I assume you meant that the caster was moved to 5°. That much camber is only used in racecars.
Second, too high a pressure on the fronts tends to cause the tires to follow the ruts and grooves in the road. What you didn't tell us was the tire size and the specified inflation for that size - not what Goodyear's charts say, but what Winnebago's sticker says.
I am having trouble with the rear tire pressures being the same as the fronts. That would be a bit odd.
And lastly, while this isn't the time of year to really test this out, have you looked at how much the tire pressure builds up after an hour of driving at highway speeds? Rule of thumb say no more than 10%, and at 15% you need more.
I suspect you are hardly getting any at all.
OK, one more tidbit. When calculating the pressure buildup, you need to back out the pressure buildup due to ambient temperature change. 3% for avery 10°F. That is, if you start the day at 50°F ambient and 80 psi, and measure the buildup later when it's 90°F ambient, 12% of the buildup (about 10 psi) is due to the increased outside temperature, and not due to operating conditions (load in particular.)
