Grafting many varieties

I have a row of espalier apple trees. I am thinking about getting a lot of varieties of scion wood and graft a different variety every foot across the top tier. I would then only allow each grafted variety to grow less than a foot and hope for a few fruiting spurs.

Is this possible? Can I keep a grafted branch at only about 8" forever and get a few pieces of fruit per year from it?

Any problems I may not be thinking of?

Not so much a problem as an awareness that you need to ensure that you choose spur bearing and not tip bearing varieties of apples to plant.

Thanks. I ordered my scions for delivery in late winter.