There is a Vallejro (sp?) station in Scotts Valley just north of Santa Cruz that would be pretty easy in and out with a fiver. If you take the north exit off HWY 17, it will be on the right as you come through town. If you pull out and turn right through town, it is easy to get back to 17 at the south exit. If you need a stopover spot, the Santa Cruz Ranch RV Park in Scotts Valley is very nice. Don't plan on taking your fiver downtown in Santa Cruz. The streets are so narrow and tight, I rarely even take the dually to town. The transition from HWY 17 to HWY 1 can be a bugger with traffic depending on the time of day you hit it. From Scotts Valley, it is about 40 miles to Monterey.
Good luck and watch out for the crazy drivers... ..... Steve