The EFI 4 strokes seem to do a lot better than that 1:10 ratio.
I went for a pretty good ride last weekend. We went from the power
lines on the Estero River to South Seas in Captiva, out Redfish Pass
for a ways and returned on a little less than 12 gallons of gas. That
was 7 hours, about 65-70 miles at 3500-4000 RPM
(60HP merc)

3500-4000 RPM is not WOT. So you would do a little better than 6 GPH.

Paul