Your call of couse, Skater, but keep in mind that the stripes were indeed very “bright”, being freshly-painted and all… There wouldn’t be much fading at all, since the weather wasn’t all that great that summer, and dirt would be the only real cuprit (evidenced in the above photo that it didn’t matter to the fitters either, if they painted right over the dirt, and then walked the still-wet paint), lol… They were re-applied to RAF and USAAF tactical aircraft for Market-Garden as well, BTW…
Dad told me, once upon a time while I was carefully masking a P-47’s stripes, that they went to bed the night of 5 Jun 44 and woke up to (sloppy) freshly-striped Mustangs themselves too…
When they went back being tasked with “Ramrods” (bomber-escort missions) the stripes were painted-over, rather than removed from, the fuselage topside, with locally aquired Dark Green and RAF-Dark Green paint… The wings were NMF, so the stripes were removed from that area with Avgas. The “official” USAAF OD stocks they had on-hand was long gone, used up… 'Course, that was unique to the 55th FG, since they used a mix of camouflaged and NMF on their Mustangs…
Here’s the CAF’s “Gunfighter” done with the “Before Operation Overlord” scheme (It’s accurate too… I was part of the research team that poured over a hundred or so 555th FG color photos during it’s restoration and repaint after the 1988 crash.). I should say that it’s “accurate overall”, with the correct 55 FG / 343 FS’s markings, since the aircraft code of “U” in "CYU" is notional, as is the name “Gunfighter” and the aircraft Serial Number. There was no CYU or “Gunfighter” in the 55 FG / 343 FS…
The “U” comes from Gunfighter’s Pilot’s last name, CAF Colonel Reg Urschler (Brigadier General, USAF Ret) … After Overlord, the under-side fuselage stripes remained, but the rest were gone, even from under the wings. Only the ETO Theater stripes remained on the wings In black) and horizontal stabs (in white on top , black on the bottom)…

However, I digress…
My point as that “scaling down” the black and white stripes may not give the “look” on a Spitfire it does on a P-47 or P-51 with NMFs… They just didn’t get to be that “old” where the black would fade from the sun and the white get that dirty… I’d recommend that one keep the white at least as “bright” as the national insignia’s “star &bars” and apply no more fading to the black than what’s apparent on the blue field…
Just an aside, I found this moving little ditty this morning… Turn it up to “Eleven” !
http://www.youtube.com/watch?v=io383HP2uEo