Pack rafting in NorCal?

There are a few people I watch regularly on YouTube and I’ve noticed an increase in pack rafting and seems like it would be fun backpacking type adventure. Are there any rivers that we have that would make for good entry level PR? I have a pretty good inflatable kayak rated for whitewater but I don’t really have the experience nor want to do that for a first time. So would like to keep it low class I/II.