They'll do OK at least for 5 years, probably longer. In 15 gal pots they need replanting every few years. After about 5 years without repotting the vigor drops below what is needed to make good fruit. Your planter is a lot bigger than a 15 gal pot so the trees should last longer.

You could get a multigrafted tree which might reduce root crowding. Getting the trees on Citation vs a more vigorous rootstock might help a little as well.

What are your favorite cultivars? Mine are (earliest to latest) Flavor Supreme, Geo Pride, Flavor Grenade, Flavor King, Flavor Finale, and Flavor Treat.

Thanks fruitnut. I feel I'm a little limited as far as selection because of my location. I've been told that Flavor Grenade, Flavor King, Dapple Dandy, and Splash should be okay in my area because of their lower chill hours.