As I have posted and illustrated a couple times elsewhere, .5-oz fiberglass with 45-degree bias really stiffens a profile fuselage and makes it quite resistant to twisting. Just opening up and trussing the aft fuselage with balsa trusses, before laminating with 1/16" balsa both lightens and stiffens the fuselage over that of a solid 1/2" piece. Here you then have a profile-legal 5/8" thick fuselage.
Phil C. uses foam and laminates for an even lighter fuselage, but I find that 1/2" balsa core (or 2 x 1/4") plus 1/16" balsa laminations, with the truss work and biased fiberglass is very stiff and torque resistant. The (biased) .56-oz fiberglass with epoxy is as light or lighter than CF veil, due to thickness and amount of epoxy necessary to fill and attach it. I weighed a couple nearly identical tails to verify that the one with CF was no lighter than the FG one. Unless you have woven CF, the glass should be noticeably better as a surface stiffener. I think that you'd achieve a reasponable result by laminating the glass under the surface laminations, with a significant loss in work and mess.
SK
SK