I love a challenge:
I would THINK anyone who normally comes down I95 could come down I95 until the I85 turnoff and then follow I85 to I75 (Atlanta) to get to WDW. This will add SOME time but will let you avoid the G8 area. I think you catch I85 roughly around the Richmond/Petersburg, VA/Henderson NC area. Since mapquest kept wanting to send me DOWN I95 I used Charlotte NC as my I85 point of reference.
Richmond, VA to Orlando FL: using I95- Total Est. Time: 12 hours, 1 minute
Richmond, VA to Orlando using I85: about 16.5 hours
Richmond, VA to Charlotte, NC Total Est. Time: 4 hours, 54 minutes
Charlotte, NC to Atlanta, GA: Total Est. Time: 4 hours, 2 minutes
I75 (Atlanta) to Orlando Total Est. Time: 7 hours, 20 minutes
Picking a NORTHERN POINT and using mapquest I came up with the following routes and plans. I broke them up into different routes because a) people will ultimately have questions about where to stop and b) mapquest and freetrip kept sending me all the way down I95. They all look like they take ALMOST the same amount of time.
From Harrisburg, PA: I81 to I77 (Wytheville, VA) to I85 (Charlotte, NC) to I75 (Atlanta) to Orlando:
I81 to I77 (Wytheville, VA) Total Est. Time: 5 hours, 57 minutes
I77 to I85 (Charlotte, NC) Total Est. Time: 2 hours, 21 minutes
I85 to I75 (Atlanta) Total Est. Time: 4 hours, 2 minutes
I75 (Atlanta) to Orlando Total Est. Time: 7 hours, 20 minutes
From Harrisburg, PA: I95 to I85 (Petersburg, VA area) to I75 (Atlanta) to Orlando:
I95 to I85 (Petersburg, VA area) Total Est. Time: 4 hours, 13 minutes
I85 to I75 (Atlanta) Total Est. Time: 8 hours, 17 minutes
I75 (Atlanta) to Orlando 7 hours, 20 minutes
From Harrisburg, PA: I81 to I40 Knoxville, TN to I75 Atlanta, GA to Orlando:
I81 to I40 Knoxville, TN Total Est. Time: 8 hours, 53 minutes
I40 to I75 Atlanta, GA Total Est. Time: 3 hours, 33 minutes
I75 (Atlanta) to Orlando 7 hours, 20 minutes