I think you could add some strips of 3x1mm carbon or some 3x.8mm carbon in a couple of strategic locations (possible additional wing spar, fuse stiffener, perhaps embedded in the wing LE), and make the new more flexible material work for another 3-5 bucks per model, at most.
I know it impacts the kit cost for you, but I did some analysis on the material costs. For me, when I buy 10 sheets of 6mm Depron, the cost is about 75 cents per sq. ft. The new MPF foam is 49 cents to 61 cents per sq.ft., depending on who you get it from. The lower foam cost could offset some or even a lot of the added carbon cost.
On my designs, I don't use carbon tube for spars. I have been using 6x1mm carbon strips. Easy to slice the foam and bond in the flat strip.