Just returned from yet another amazing 3 days of camping in Rancho Oso....a campground owned by the Thousand Trails system and located east of Lake Cachuma, it is an awesome place to trail ride. There are miles of trails along the Santa Ynez River and up in the surrounding hills with incredible views.
The campground itself has a number of types of housing. From tent camping on the ground with very nice bathrooms/shower units nearby to modular log cabin style homes located near the 2 swimming pools and spa. But the best part of this place is that you can walk your horse right into the river and take them for a swim!
Yep! You just drop off your saddles and boots on the dry river bank and walk your horse in. Mistake I made was taking it a little too fast (hard not to be excited about this) and my mare was not happy about having swim for the first time in her 8 years of life. So she high tailed it for the nearest bank where I almost slipped off of her as she charged up. But we made another attempt, this time much slower, and she loved just standing in the warm water up to her chest. Next year I'll take her a bit deeper and she'll realize that it's really more fun than she thought!
I highly recommend this facility as well as a number of other places to horse camp within 2 hours of Paso Robles. Plus many, many places to day ride your horse. Oh, and if you're new in the area, I can recommend some great trainers to help you and your horse brush up on your skills. You're going to want to ride LOTS when you move here!