Reinforcing the firewall in my case is more than necessary. It is a strange story: somehow I managed to pay and receive the Skybolt ARF from Tower Hobbies at the price of the kit ($100 less) but the firewall at its left side is not glued correctly with the fuselage and the only thing that keeps it is the triangle stock from behind. I cannot return it to TH because they will probably find out their mistake and charge me more. I intend to drill 4 holes at the points that the firewall touches the crossed ply structure of the fuselage (the parts that form the tank area) and pass through them sticks (haven't decided the wood type or dimension yet) that I will glue for at least 2" behind the firewall. It is a little more complicated than what I can describe here and a picture would say a lot more, but that is planned for this weekend. To facilitate this I will probably have to open a hatch at the bottom of the fuselage, where the exhaust goes. All that added weight and the smoke setup, will need some extra power than what the FS91 can give.
As far as 3D, yes, I may have exaggerated. I know what the SS is. Anyway, I'll post some pictures if anyone is interested in what I intend to do. All my decisions really come out from what I've read to this thread, so thank you all, it is very helpful, even if it is experience read and not acquired the hard way!