Depending upon your joint configuration you may still be able to use the 2209. Simply use a joint configuration that causes high dilution with the metal. This will bring the filler into closer chemistry with the base metal.
For example, wide bevel angles, narrow or non existent root gaps, and feather edges. With this joint design you will see significant dilution from the base metal.
Or perhaps even an autogenous root.
The only other choice I could offer might be a PH stainless steel (which runs the danger of Cu or Al content) or a ferritic stainless steel. Id recommend the joint design.
However, whichever you choose, you need a welding engineer and some tests.