I have a 2003 F250 with 5.4, has just under 200,000 miles on the clock with the ORIGINAL belts and hoses..
DD has started driving and she is using that truck.
Have had MORE trouble with the steel brake lines, transmission lines and power steering lines, emergency brake cables rotting from road salt rust than with soft stuff like belts and hoses.
Do a visual check on the belt, no signs of cracks or excessive glazing an you should be good to go for a long time.
For hoses, do a visual AND feel test, good hoses with have a solid feel, hoses that are end of life will often get soft spongy feeling in spot places.
Additionally, check your vacuum lines, the modular blocks have a habit of breaking some of the vacuum lines on the engine where the lines get hard from the heat.
If you feel uncomfortable driving long distance on an old belt with no cracks or glazing, then change it if it makes you feel more comfortable.
You should be more concerned over the condition of the steel brake, transmission, power steering and fuel lines.. Especially so on a RV that sits a lot and or has a lot of salt exposure (road or ocean), this is more likely one of the problems you will end up with..
My transmission line failures so far have occurred right at the radiator where the lines connect to the cooler in the radiator. If they have a layer of heavy rust scale you WILL need to take action and replace the lines.
The brake line failed behind the fuel tank, couldn't see that until it broke..
