I think you'll be fine there, Crazy01. You have several years to go, yet, to worry about trees getting too tall. I would suggest purchasing semi-dwarf or dwarf cultivars, so that will help to remove the height issue. Drop-crotch pruning would be the technique you're after to keep the height down if necessary. Three feet is close, but again, if you purchase semi-dwarf or dwarf cultivars, that, plus being in a container will keep size down. You should be fine. I have two container citrus that are about 3' apart right now, and they aren't close to each other, yet, and if I keep the container size limited, they will stay that way (may need root pruning several years down the road to keep size down.) My only concern is the lack of sunshine. 4 hours is almost not enough. 6 hours would be the minimum for good quality fruit. Use a very well draining potting mix - we have a couple of great recipes on our forum, just search for "gritty mix" or "511 mix" for the ingredients. Also, Farfard makes some excellent professional mixes you can purchase as a pre-bagged product, if you can purchase Farfard in your area. Lastly, remember to fertilize properly. Most of our container citrus folks as well as myself like to use Dyna Gro's Foliage Pro with each watering, and I also use a time release higher nitrogen fertilizer as well, since my container citrus are out all year 'round like yours will be. Container citrus need more fertilizing due to their more artificial environment being in pots. I do a water flush about every two months to flush out any built up salts from the fertilizers as well. Good luck and please share your photos with us when you have your trees planted.

Patty S.