I'd agree with Dave. I drove quite a few "moderate" trails in AZ before I added heavier bumpers with only minor damage to the stock bumpers. You will feel much more comfortable with sliders though, as damage to your rocker panel area is expensive to fix. As T mentioned Stubbs Welding sliders, I also have a set and he is great to deal with.
For trail running I sort of go with the idea of "use what you have" and you'll figure out what you need. If you find your stock tires aren't up to the task, then by all means upgrade. Otherwise you'll see stuff on the internet and stuff on other people rigs on the trail and then you'll have this huge list of stuff you want, that may or may not be what you actually need.
Don't forget a few bucks for basic recovery equipment.
One question: does your truck have a stock e-locker?