Late to the party, but we did WDW to DL in 2015. Well, it was actually from Nor Cal to WDW and then to DL via the Smokies. It was great!
We boondocked all the way to FL and most of the way to DL. We only paid for camping at The Fort, in the Smokies, and RV parks for a few days in Denver then at DL for the 24 hr kickoff for the 60th.
You'll have a great time. The Fort is by far the best RV park we've ever stayed in.
We're hoping to do it again in 2018.