I’d like to add onto what some others have said. First, if you aren’t an experienced grafter, you may be very disappointed with your success rates when it comes to grafting peaches. I’ve been grafting for about 8 years and I get about 15% of my peach grafts to work. Plums much higher, and apples and pears are in the 90’s. Peach grafting is HARD, as others have said. Also, if you have visions of just creating a nice peach tree with many varieties that you can just maintain and then harvest, it won’t be like that. WHile there are certainly people on here who have multi-graft peaches and do ok with them, lots of us get tired of all the maintenance and then dealing with those grafts that die in future years. Many varieties grow at different rates, so you’ll end up having to constantly prune some of them back several times a year while others won’t grow much at all. Then when one and then another graft fails a year or two or more later, you have to deal with a big empty section of your tree, and by then there is often no good graft position where you need it. I know we all love the idea of having many kinds of peaches and plums on one tree. Its a neat idea. But in my experience and that of many others (not all) multi-graft trees just aren’t the idealized option they sound like. You’d get a lot more fruit and much easier if you just picked one good peach tree and grow it out. The fact that your tree will be 2-3 feet from a fence is going to make it that much harder for you to have a good multi-graft tree.
Not trying to rain on your parade, just giving you some realistic and honest information to try and save you a lot of hard work and disappointment in the future, We have all seen those photos of beautiful, multi-grafted trees with different colored blooms and lots of fruit varieties hanging on a neatly balanced tree, and they look amazing. But like many things in life, they are mostly just nursery-created photoshopped pictures or are trees made and managed by true fruit tree experts who spend countless hours developing those trees. A beginning grower is unlikely to end up with a result to match those dreams and photos - though some here have done it. Good luck.