Since you've got your defenses maxed, I think you should go up to Masters (try M3 first and see how that works out). You will be able to comfortably farm gold and DE with loonion, and if you have some gems and time to boost, boosted loonion is very fast (12 minutes or so to train). The elixir cost is pretty large for a loonion army, so mostly you'll be upgrading walls with gold. As for DE, it's very, very easy to come by in Masters. The minions will cost 500-600 DE, depending on your loonion comp, but the league bonus and the amount you should make in raids (frequently 4000+ per raid including 1000 DE league bonus) more than makes up for that. I have seen many late TH9s up in masters loonioning and they've maxed their walls and heroes nicely.
You might want to try to mix in some lava hounds and do LavaLoonion for some extra power. Use them sparingly though; they're expensive. As for spells, carry 2 heal 2 rage, and a poison for CC troops maybe.
Another thing you can do in masters is snipe for the league bonus (120k G/E and 1000 DE). I racked up quite a bit of loot doing that a couple weeks ago.
All that is if you want to do walls and heroes. If you want to crank walls as fast as possible, stick in mid to upper gold leagues (1500-1900, best spot changes day to day). You won't be making serious DE here though.
Hope I helped, and best of luck maxing your royals
By the way, my defenses are TH8 level still (except for mortars and xbows, they're maxed). But in terms of walls and royals I'm pretty much in the same position as you. About half done with legos and my royals are 12/12 I think.