There are a few easy (green) and moderate (blue) trails at Hollister Hills that you can run without scratching up your brand new truck. I was there a couple weeks ago and drove most of the park with a group of 3 rigs. Here are some suggestions -
1. If the trails are dry, head into Hudner Ranch and run Hudner Pass (green) to Valley Vista (green) up to the parking area on the left. There is no overhanging brush at all on these trails as they travel through grasslands.
2. In the Upper Ranch, McCray Road (green) to the right turn on Garner Flat Road (green) is easy on wide roads without the risk of scratches.
3. Foothill Road (green) is a loop around the lower part of the Upper Ranch. There are a couple narrow spots but you can easily get through without scratches.
4. Most of the middle section of McCray Road (blue) is wide without brush but once you get to the intersection with the top of Fremontia Road, there are a couple rocky sections that can be challenging for a less experienced driver. The view from Hector Heights, the high point of the Upper Ranch, is a great reason to give this section a try. There is a slight chance of scratches in a couple spots but if you are careful you should be fine. 4 LO is a good idea on the section above the top of Fremontia Road.
5. Prospect Road (green) to West Trail (green to blue) and up to the Quarry is easy and wide. Above the Quarry West Trail (blue) has a couple rocky sections where 4 LO would be helpful. You can take this up to McCray Road (blue) turn left and come back down the hill easily.
Here is a link to the online map -
http://ohv.parks.ca.gov/pages/1170/files/hollisterhillstext_upperranch_final.pdf.
Make sure to ask for a map when you pay your fee's in the Lower Ranch at the kiosk. There is a sign posted there that will let you know if Hudner Ranch is open or not. They close it when it is wet.
Good Luck with your new rig!