Well, it has been shown to work.
Yes they did. The Manhunters where featured in an episode which loosely adapted the destruction of Xanshu story. Katma Tui was also in a seasonThe DCAU didn't do any storylines that used Green Lantern Stuff.
The DCAU used very little of Hal's character for John. The only thing they "stole" was Sinestro (who is an enemy to all Green Lanterns) and being a founder. I don't see the comics stealing anything from Hal that wasn't available to all Lanterns in the first place.He also works fine as a League member, you only get this problem that you need to "steal" Hal Jordans stuff if he gets promoted to a founder and the first human Lantern, and you give him solo stories.
Hell, if anything DCAU Kyle stole way more from Hal than John did.