I tried a couple of different things, so I'm not really sure which one worked, but this morning now that he's dry again, he definitely smells much better. Not 100% better, but 80% - I guess that's good. He was SO stinky last night, I was afraid I'd never be able to pet or hug him again!
First I used some moistened baby wipes - did nothing.
Then, I used doggie shampoo and water - also didn't seem to help, but masked the odor a little bit.
I didn't have any lemon juice, but I do have vinegar. Leo hated this, but I think it helped. I couldn't tell at the time, because when he was still wet, he still smelled. But now that he's rinsed off and dried off, he smells pretty good. And, now his coat feels really soft, which is a bonus.
And Leo is clean and we are snuggled up on the couch together as I write this, and all is right in the world again! Thanks for the advice!