Probably not as hard to do as you'd think in any NLE with CC.
Find the two points of the extremes in color error and correct each of them. Vegas will create a keyframe at each point. Now just keep finding the next matching points and copy / paste the appropriate keyframe. As this is cyclic you could probably soon get the interval of the thing sorted.
Hmmm.. It would be interesting if one could use an ADD to an upper Track that would reflect any need to change the WB? . . We got a Deshaker script. How about a varying CC that would adjust to keeping a WB at a preset level? Only the musings of a video delinquent here.