Rv-6 tanks on the -4
Mayor,
I built a -4 that was certified in August last year. I used the long-range tanks that fit into the leading edge lightening holes. Gives me 8 gallons, or about an extra hour of range. They're made by Hotel Whiskey.
If I could do it over, I would have simply used RV-6 tanks and saved at least 10 pounds of weight and the complexity of 4 tanks to manage. I also cut down an -8 slider canopy and completely did away with the center roll-over bar (far better visability for you passenger). It's a great airplane, and if your wife/girlfriend is under say 140 pounds, it's just fine for cross country.
That said, I'm looking at building the F4 Rocket-Lite. Mark Friedrick's F1 Rocket with a 4 cylinder IO-360 instead of a 6 cylinder up front. Seems to me this is the ultimate upgrade from my airplane, which I love. The F-4 is faster, still a 4 cylinder so not much heavier, and has more room for both pilot and passenger. On paper that concept is hard to beat in my opinion. We'll see when the first few actually fly.
YMMV,
Ron
RV-4 / N8ZD