Having Junior marrying into the Orleans line doesn't really help - they will still see him as a threat, which he is, and he is supposed to keep the French power in check. Besides, it will harm his image among his supporters. Austria will be his major supporter and I can even see the Austrians remaining neutral or even supporting Eaglet financially if he tries to take over France. Russia and Austria had a pretty harmonious relationship at the time and I can see Austrian diplomats working their magic on the Russians. That leaves Britain, which will not go to war alone and MAY be satisfied with Napoleon II renouncing his claim. They will still be wary of the man, though. Just as Dutch will be. Bourbon France will be kicking and screaming, so to say, but they can't really do much about it in case Napoleon II falls in line with what foreign powers demand he does. At least, for a time.
You still need him to marry someone suitable, someone, who will help his aspirations and Imperial dreams. Means, not Austrian cousins (no need for Habsburg inbreeding), no one from Italy (because Sardinia has no one suitable and Naples is useless), no one from Spain (because the Spanish will likely hold a grudge and are too weak to be of use anyway) and no one from Scandinavia (because they won't help much).
I'd suggest Princess Louise of Prussia or someone from Bavaria - princess Ludovika Wilhelmine or Maximiliana Josepha Karoline (if you have her live longer than OTL). Maybe, in order to appease the Dutch, have him marry princess Marianne.
Like I said, TTL 1848 will be his best chance of winning. With the Bonapartes in power in Belgium, Imperial underground can get organized and become a viable threat, having Belgian support. If Bourbons are still in power odds are the French people are even angrier at them than at the Orleans dynasty OTL. 1848 kicks in, other foreign powers have to deal with their own rebellions and Napoleon II uses that as an opportunity to take over France. Preferrably, swiftly and with as little blood as possible. He can be even secretly allied to Austria and, depending on who he marries, have allies and/or sympathizers in Germany and Netherlands. Hence, it can be pulled off. I won't lie to you, this will require A LOT of luck, but Bonapartes have a history of pulling off some awesome feats rather unexpectedly, don't they?