Thanks for the question, Danny! I can't answer this from experience, but I have some ideas:
This was your idea, and it's a good one. The only problem is you're going to have to have some good friends to jump into this for you, but you'll both be better for it :).
Code review is a team effort, so maybe you should consider finding a pair to rock out the hard problems. If you don't know anyone specific or you'd just like to diversify, check out the #pairwithme hashtag on Twitter.
This can be surprisingly effective. You won't get the benefit of knowledge sharing with others, but you will get the benefit of a fresh, high-level view of your implementation. Even on a team, I do this all the time! I'll create a PR for the purpose of viewing my commits in one place. Then I'll go through them just like I'm reviewing someone. Seeing my work after the fact is a really great way to catch bugs and consider design, and the comments are perfect anchors to attach actionables. Try it out, maybe it'll work for you!
Thanks for the great question. This may be worth a future post of its own! Stay on the lookout :)
Thanks for the in-depth answer!
Ask a friend - this is probably more like a lifeline...use sparingly, but results will be great.
Pair programming using #pairwithme sounds interesting - I may give that a shot some time. Awesome that it's a real thing and random-ish people team up. Airpair.com seems to have brought it to a professional marketplace level.
Code review yourself - this is where I'm at now. I occasionally will go back over last week or last month's code and comment / analyze it in depth. I would benefit from having a more disciplined practice to the self code review.