What do you have on the outside of the dimensions listed? ie. are the trees able to overhand that area or is it a wall/fence? I recently did a planting of trees on a fairly similarly sized area - you can see my plans and planting. I am doing all my trees open center for what its worth. I managed to get some with interstem roostock B118/B9. Seemed the best balance between dwarfing/good roots.
I am not sure how much tree research you have done so far but if you have not do some research into disease resistant apple and your local pests. Consider what you are willing to spray to make this work. Although cider can still be made from buggy apples!
As for wanting to do open center - @Jsacadura seems to keep his open center and has lots of good videos - I found his videos some of the easiest to understand for a beginner. There is also Stephen Hayes who is a bit of a legend here who keeps his trees open center. Standard thinking against open center is that it produces less per unit area (which is why I think most commercial growers abandoned it) as well as prone to branch breakage due to all the scaffolds coming from the same location (can be reduced by a modified center leader or modified open center approach or just being mindfull with fruit load)
+1 for reading Grow a Little Fruit tree - I have found it inspiring.
Most of my knowledge is theoretical. With any luck I will have my first peaches this year and apples next year.