JDM von Weinberg , Apr 05, 2012; 07:30 p.m.
every suggested solution is an awkward kludge
Unfortunately, this is pretty much the "state of the art".
If you delve deeply into the arcana of the ViewScan 'manual', you may, repeat may, find a way to preset the scan size in using the VueScan software for your Epson, or even a way to use the automatic edge sensing to do the job.
Lots of luck. I don't know the Epson software/hardware capabilities.