On a whim, on clearance, I bought what looks like a 2 year old red flame seedless grapevine at the box store. There are two "trunks" growing from a pruned woody fork (1st yr growth?). These "trunks" are now about 8' each with other branches coming off as well.

I have a small yard. After fretting over the perfect location at home, the best spot for sun, air and drainage will require the mature width to remain about 6-7 feet wide. (There are young fruit trees on either side that will eventually grow wider, hence limiting the grape width).
If I run the trunks up about 3-4 feet, and then angle them horizontally out on a wire, can these trunks (which I think become cordons) be cropped to 3' on each side permanently?

Thanks in advance for any advice!

Mine were great this yr. Trimming off the tips of bunches helped.

Google "Head Trained" Vines. Those are vines that have one trunk and 4-5 cordons about 6" long. Canes come from those, bear fruit, and are then pruned back each year. Those vines look like little trees. Because our young vineyard is on a steep hill, we decided to head train ours.