I adhere to Elder Futhark when it comes to runes, so I'm sure we're not on the same page when it comes to Sowilo.
Chaotic magick is actually a completely different magickal practice. I know nothing about dragon magick, not sure I fully subscribe to all that, but I'm pretty sure summoning a chaotic dragon doesn't involve the practice of chaotic magick. I'm sure the two arts could be combined though.
Sigils are great practice, for the most part. I've really gotten into the incantations though. It's a little more risky, but SO effective!
Have you ever meddled with the incantations?