My friends and I took the cruise to Santa Cruz Island for a simple 1-night backpacking trip. It's only 4-miles from harbor to campsite, but it's mostly uphill. My friends were beginner backpackers so it was a bit tiring, but it was over quick and I still think it's a great trip for beginners. We arrived at the campsite and pitched two 2-person tents on the sand pit. When we woke up everything was damp from the seaside fog. But the fog made the views quite lovely. Saw lots of island foxes - so cute!
Note that there are gear restrictions for the cruise (check the website). Also you have to PACK YOUR OWN WATER. And use the food storage boxes to protect your food from the foxes (or bears??? JK).