Your doctor is going to be SUPER conservative about his advice, they always are. They cant risk giving you any clearance to ski because if you get hurt doing something dumb (like in the park, or hit by a gaper), he could be sued. A few years ago, while watching a mogul comp on tv, they listed some ridiculous stat of the competitors and if they had ACLs or not, something like 60% of the competitors had blown out both knees are were still competing, without surgery.
You'll be cool carving some turns on corduroy, my advice is to restrict yourself by getting a pair of non-twins or race skis so you wont hit a rail or anything.
Do what you want, but plenty of people make turns without ACLs. I think youd be in much more control skiing regular than trying to monoski, which is really hard to learn (I've tried), you'll prolly take at least a few spills.