Peter pretty much captured the direction I was going along, so I'll use his suggestion as a starting point. I'd make the C shaped green go around an inlet of water rather than a bunker, creating a go/no go option on the second shot when the pin is on the back part for those who play it safe and lay up off the tee and making sure that hitting it to 50 yards isn't necessarily better than leaving yourself a full wedge if you want to put it close.
I'd put a big depression (I'm talking 10-12 feet deep so that you can barely see the top of the flag from down there) starting from front left up to mid left to capture those who shy away and encourage hitting it a bit deeper. No sand, just grass, preferably closely mown to allow the player to choose between a flop or a putt, as well as make it roll back to your feet for another try if you get too cute with it! Make for an interesting recovery shot from there with the lake waiting behind!
Not sure about how much to shorten the holes, if at all, but I'd leave 3 shorter than 12. Both should be potentially driveable, but you pay for the shorter shot to drive 3 by requiring a draw (or more of a draw, depending on how many trees on the left are removed) You'd want the shot on 12 to be pretty much straight. Doesn't sound like its an option, but I'd want the flag for 3 always on the front part (to encourage the draw drive to go for it) and the flag for 12 on the back part (to get the maximum fun from the difficult green complex)
I'd leave the fairway open, there's no reason to get nasty on the tee shot for those who lay up or can't manage the distance, all the fun comes in when you get around the green anyway. No bunkers, no ridges, don't even try to make it narrow. The wider the better, let the player choose the angle to play in from, there will be advantages and disadvantages from every angle, and from every distance. I want the player standing on the tee thinking of a dozen possible options and not knowing which one is best.
Definitely want to cut down every tree on the right, give a nice view of the lake, both for aesthetics and intimidation.