You don't need rockwool. You could use rooter plugs, pieces of styrofoam, or you could probably get away with just using the hydroton assuming you are careful not to jar the rubbermaid until a root system is established.
I sat hear and thought about it for a minute smart bad but i think tahh you could use something like jiffy peat disks to do your clones in and then just put those in the rockwool but i am not sure what were your ideas
i have never tried it but i think if you use the disks, and make them in that kind of solution and throw some superthrive in for good measure and them use the powder on the roots you should have very good results i would recommend squeezing out the disks a bit before using them for your clones. I think you would have good luck with it and the peat disks will eventually for the most part dissolve into your res.
Oh when i used it for my seeds i took the net iff and used the peat in smaller containers so the roots didn't get light. I dunno if that makes sense lol