How old is the truck? If older the radiator may need flushing. Anything over 5 years old and pulling a load I would flush it about ever 3 years.
If you have a clutch fan and you did not hear it come on it may need replacing. Those clutch fan have a very wide range of On Temperatures and you may have one that is on the high end or as noted it may just be bad.
Even with a working clutch fan and clean radiator I would consider installing an electric fan with a thermostat and manual switch. This way if all else fails you can hit the manual switch and cool things down.
As for the low oil pressure 35 PSI should not have set the light. Most low pressure switches won't come on till below 10 PSI. You might want to have the oil pressure switch checked to see if the gauge is correct.
WBCCI 12156 AIR 3144 WACHUNG TAC NJ6
2004 Excursion 4x4
1991 34 ft. Excella +220,000 miles, new laminated flooring, new upholstery, new 3200 lbs axles