Using addon domain for development

I want to use the addon domain http://www.beacheslock.com/wp/ as a development site. Because the site will have close to 300 items for sale using WordPress eStore plugin, I want to develop the site in http://www.beacheslock.com/wp/. When everything is working I want to have all site traffic resolved from http://www.beachslock.com to http://www.beachslock.com/wp/. I want to do it this way to reduce errors to zero when live traffic visits the site and starts purchasing product. My question is: is this a sound plan?

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