Why do you think your fuel needs polishing? Are your filters clogging
up? When I first bought my boat, I shocked it with Soltron, had the
fuel polished, and kept using Soltron and am very happy with the
results. The dual Racors are a good idea... you can accomplish the same
thing with plumbing as replacing current singles with duals. You just
have to be able to switch over from one to the other with a 3-way
valve.

If you decide you need to polish, and may need to do so in the future,
you can build your own polishing system for what it costs to have it
done once. I built one like this and use it as a preventative measure,
since I carry 700 gallons, which can be a year or two worth of fuel for
me. See:
http://www.gulfcoastfilters.com/fuel_polishing.htm

The heart of the system is the GCF filter... you can use a continuous
duty Walbro pump to pump the fuel through there.