When making material substitutions, especially for primary structure, one must arm themselves with enough knowledge of the new material's characteristics.
Here's my take on using CRES in our construction:
CRES ("stainless steel") resists corrosion via the formation of a naturally-ocurring (i.e. naturally-forming) oxide layer. Aluminum does the same thing, by-the-way, albeit with a layer that is not quite as robust.
When CRES is machined, bits and pieces of ferrous metal (from the steel tooling) become embedded into the CRES. These are potential corrosion cells, and if not taken care of, a sometimes insidious corrosion problem manifests itself.
The means to address this situation is via a process known as passivation. Passivation typically entails treatment in some sort of acid, so as to remove embedded surface contaminants and help form the necessary oxide layer, at the same time.
Nastier still, if unpassivated CRES is potted in or embedded (like lift tabs would be), there is potential for accelerated corrosion internally, and right at the bondline because the bonding surface does not allow sufficient exposure to the environment such that a naturally-occurring oxide layer forms, yet it can still let moisture in via small pores & such at the bond interface. The mix of trace moisture and ferrous cells in the CRES make for a great corrision scenario.
IF I were to use CRES, I'd, well, not opt to use it. The beauty of the aluminum tabs is that one can do a great corrosion-preventive treatment for them in one's own garage (as opposed to passivation of CRES & such). If you absolutely HAVE to use CRES, well, 302 1/4H or 304, 1/4H, with all proper passivation, could work, but I cannot absolutely qualify it's use in such an application (i.e. I cannot make any reccomendation for it's use on someone else's airplane, and I would not use it at all on mine).
I am an engineer in the airplane biz, and I can comfortably state that there is NOTHING wrong with plans-built lift tabs. I have evaluated many aspects of the composite canard design (strengths, servicability, corrosion prevention, etc.) from an engineer's perspective, and am quite comfortable with my enhancements to the basic design (e.g. Alodine on all aluminum parts that cannot be replaced, use of good primers and paints on metal parts, etc.). For corrosion protection, a proper Alodine treatment is sufficient for corrosion resistance. If one is worried about moisture ingression into a glass/metal bonded area, application of a good automotive urethane sealant, or aircraft sealant (e.g. ProSeal) as a fillet seal around the metal will work well. I have a VariEze, with embedded 2024-T3 wing attach fittings. I applied Alodine, and after installation, made fillet and periphery seals with ProSeal (BMS 5-95 - Boeing's Spec) around all of the installation, prior to primer & paint. I am 99.99999...% sure I will not have a moisture ingression and related corrosion problem. The VariEze wing fittings are far more susceptible to corrosion than lift tabs.
Properly made & installed 2024-T3 works well. The tabs are good for over 20 g's in a Long-EZ installation. Your F-22 bulkhead will disintegrate before the tabs go bye-bye. If one is worried about durability (i.e. being a klutz and bashing around the tabs when the canard is off the airplane), one could "up" the gauge of the tabs to .160. Note that the Berkut uses .250-thick tabs. However, I maintain that if your work style is such that you cannot protect critical parts of the airplane from incidental damage, maybe you should stay away from building your own airplane altogether...
Does this help?
