I am not aware of a timing belt needing to be changed on a DP?
You might want to check your serpentine belt and AC compressor belt for condition.
Find a Speedco or similar and and have the engine oil, oil filter, fuel filters and coolant filter changed (if you have one). This will give you piece of mind.
Check the transmission oil level. That service likely can be deferred until you have more time to become familiar with your rig's situation.
The trip you describe is not a long trip for a DP, so it is likely that just checking fluid levels in the engine, transmission, hydraulic fluid tank, and batteries is all that is essential.
The largest trip condition concern for me would be tire status.
Once the tires are more than 5 years old, inspect them for cracking as tires age out rather than wear out on a MH. Look on the interior side as well as the outside of the tire sidewall.
A blow out is a safety concern but also may take out some fiberglass at the same time. So tires require a bit more attention than on an automobile.
1995 38' CC Magna #5280
C8.3L 300hp Cummins, 31,000lbs
Gillig Bus Chassis 05 Jeep Wk