If you have good Ballance it is possible but it takes some practice get use to sitting and maneuvering before trying,take that from someone that is 63 and do it in water at least 3 or 4' deep with no rocks.
My kayak did not come with a paddle. 07 June 2016
I would call Lifetime to see if any of their other backrests might be compatible. The Customer Service telephone number is: 1 (800) 225-3865
I don't see it on any tags but I can tell you I weigh 200 lbs and that is not even close to over loading. It is designed for single user but even with 50 lbs of gear it would be fine. Remember, this is a sit on top style, your center of gravity is higher than if you were sitting on the bottom. More weight, higher equals less stability.