Too many miles on truck before long trip?

You can catch most problems with preventive maintenance. Pay attention to the things that aren't checked often. Typically belts and hoses, as if either of those items break, you are on the side of the road. Belts shouldn't have much in the way of cracks on the ribs (preferrably no cracks at all). Hoses shouldn't be brittle and shouldn't have too much flex. Look for ballooning as well. Are your ignition cables good (do you even have them?)? Are you leaking any fluids? If so, do you know where the leaks are from and what fluid is leaking? Are your reservoirs topped-off? When was the last time you changed thermostat(s)? Waterpump? Alternator? These are all the common points of failure I can think of.

I personally wouldn't worry if your truck has been well cared for. Many rigs can hit north of 200k just fine with no major issues.