The RV line is designed around commonly available and standard materials. This means there is plenty of opportunity to shave ounces without a complete structural analysis. Many of the structurally insignificant subsystems that are installed on these airplanes are far heavier than required. Take the brakes on my Rocket for example:
I have rebuilt the rudder pedals to incorporate bushings in the pivots instead of snugged up bolts. While I was at it I decided the crude and heavy brake pedals had to go. Additionally, I tried something different with the brake line themselves and went with 1/8 OD stainless and compression fittings at both ends. I figured if Van used plastic tube and compression fittings, then this should be worth a look.
Heres a graphic illustration of just how small that 1/8 line is. Same size as the FI lines on a Lycoming. Very easy to work with.
I machined a pair of firewall fittings which accept 1/8 NPT fittings. On the cockpit side they are AN nipples for the existing hose.
Nothing wrong with the existing brake pedals except they were not done very well and way heavier than required. The flat part is 1/8 plate riveted with #30 fasteners to that heavy extrusion.
The new parts start with a hoop of 1/8 X 3/4 strap with the web being a folded up piece of .032 sheet. The good news is that I reduced the weight by 50% with the new parts, but the tradeoff was about a day spent to save 6 oz for the pair.
Build the structure to plans, but be VERY careful with subsystem installation and I'll bet you will have featherweight.