If you're going to be going south on 101 to Paso Robles then you can make a small detour - from 880 go north on 101 to the DeLaCruz exit. Make a left at the top of the off-ramp and then a right after you cross over the freeway, onto Central Expressway. The first light will be Lafayette - turn right and go to the second light. On the right will be a Rotten Robbie station that has a real good turnover of diesel fuel, and when we used to buy diesel it was one of the lowest price places in the area. - Our crew cab F450 with a 37 foot fifth wheel fit in the atation with no problems.
Farther south, on 101 take the Tennant Rd exit in Morgan Hill and go right at the end of the off-ramp. Get in the left lane and you'll see a Safeway station on the left at the corner of Tennant and Monterey Rd - a bout 3 stop lights if I recall. Again easy in and out for large motorhomes, and the diesel is reasonable. If you have a Safeway members card you get a discount based on how much you spend in the store. We just filled up our gas motorhome there this morning - the pump price was $3.899 per gallon, but with our Safeway card we got 10 cents off per gallon for the first 30 gallons.
If you want to stay right on the highway, the Garlic Farm is a good choice - and the campground there is a nice place for a layover if you need to stay the night.
