It won't be this summer but if you are serious start learning about the permit system and making a list of the skills and training you need to do something like that. Required equipment, rentals, etc. I would read some of the books by people who have done it solo in the recent past such as River by Colin Fletcher. Of course you can go back to the Powell journals, Buzz Holmstrom, etc. I believe Colin took a couple week course on how to whitewater row, river safety, etc before embarking on his solo of the entire Green/Colorado.
I'll agree with the others, boating alone is generally considered not the best thing to do in a sport where safety is always foremost for most of us, but if you are dead set and that's how you roll you can do it with the right preparation. One good thing if the Grand Canyon during summer is what you are set on, you can plan on at least seeing several groups a day and generally will have other people to run major rapids with. It's remote but not a complete wilderness experience from that perspective. Don't take it lightly though, casualties happen every year.
let us know what happens.