Yes, using WP-CRON will work for this well. One way to do it, is to set a new cron for immediately with every page load. Do not give the job a unique name. By default, WP-CRON will only take an action once every ten minutes. So in the case where your site is being hit a lot, the cron will run every ten minutes or so. It runs its’s own process, so it shouldn’t slow your system down. The 2 hour idea is a waste because it’s more work for no gain.
The benefit is that it’s easy, and will update the cache every ten minutes. The drawback is that if NO ONE visits the site, the first page-hit will be the old cached data [which will then initiate an immediate cron]. Note if this data is only accessible to logged in viewers, or you have to click a menu or ANYTHING, that will set off the cron in the background.
So yeah, it’s a good approach, probably the best approach to load cached data in the background.