There is some good info
From cafe foundation has done reports on RV-4, RV-6a and RV-8a
The only one that list flat plate area and drag estimates in detail are for RV-6a; granted that its not a RV-3 they have identical span and the flat plate ignored gear.
RV-4 (Dave Anders highly modified and arguable fastest RV)
http://cafefoundation.org/v2/pdf/RV-4.pdf
RV-6a (typical built by individual)
http://cafefoundation.org/v2/pdf/RV-6A Final APR.pdf
RV-8a Factory Demo plane
http://cafefoundation.org/v2/pdf/RV-8A APR.pdf
From the RV-6A calculated data:
-6A N157ST Serial Number 20075, power 180hp O360, Prop Fixed pitch, Bernard Warnke, Maple, 52, laminations, 70 x 74 in
Flat plate drag area** 2.32 sq ft
Oswald's e, span efficiency** .851
Cdo, zero lift drag coefficient** .021
Cl max, maximum lift coefficient** 2.136
Propeller efficiency, η, ** not available
Thrust horsepower @ 7079 ft.** 126 hp @ 199.7 TAS
Thrust horsepower @ 9058 ft.**111 hp @ 191.6 TAS
Carson's speed, V for best speed/drag** 121.1 kt/139.5 mph
V for max lift to drag** 92.0 kt/106 mph
V for minimum sink** 69.9 kt/80.5 mph
Maximum lift to drag ratio (glide ratio)**
11.39Minimum glide angle** 4.7 degrees
Minimum sink rate** 749 fpm
Minimum drag** 134.3 lb
CAFE Challenge score @ 176.6 TAS 687,385. (neglecting climb/descent legs)
CAFE Triaviathon score 148.8
For the full report go to Cafe foundation.
From Van's Specs:
The RV-3 has a wing area of 90 sq-ft, 19ft 11in span, wing loading 12.22 lbs/sq ft, power loading 11.0 - 6.9 lb/hp
The RV-6(a) wing area is 110 sq-ft, 20ft 2in span, wing loading 14.5 lb/sq-ft, power loading 10 lb/hp
From Vans specs a 150 hp RV-6a top speed is 196 mph. A 150 hp RV-3 top speed is 207 mph. As a rough estimate, the RV-3 has about 25 hp less drag near 200 mph than a RV-6a. That is shown by Vans spec top speed for a 125 hp RV-3, 195 mph, about the same as a 150 HP RV-6a.
EAA magazine had an interesting article on drag and front plate area of different homebuilts in the last few years. I recall the little w seat retract Glasairs and Lancairs are in the low 2's of sq-ft. However the new Lancairs sit taller for comfort, since many did not like laying on their back to fly. Also they sacrifice wing area (like 25% less) for less frontal area but higher stall and sink. Of course its way more than just frontal area or flat plate area equiv. Variez or Longez is way more efficient than a RV but than you will not fly them in and out of a 1000 foot grass strip, or carry as much payload or cargo as comfortable. Original 2 seat Glasair, Lancairs can be a few mph faster than a RV, but you give up short rough runway performance and simple fixed gear.