Low Water Selway

Just got a last minute Selway launch for July 27. With this water level how light do I need to pack - backpacking dehydrated food ? Also we are a family of 5, how big a raft can I get away with? I own a 16 foot rig that I love but am considering renting a 13 foot , not sure how to fit all 5 of us in that size though. I am expecting to get out and drag off some rocks but don't want misery.
Looking forward to getting on this run. Lots of previous experience rowing.