Hopefully that bit of oarnge will not be too heavily silted or otherwise covered if it is lying free.
Then a good photo interpreter will have a fighting chance of picking it out.
Part of my emergency kit is a rescue streamer, comprising a 6 inch wide x 20 meter long ribbon of plastic.
I've suggested before that the FDRs should deploy material that can aid its recovery underwater or if buried in mud. The box could have an outer frangible shell containing very long ribbons of metallic material, or perhaps slow (50 day) release dye.
We seem to be able to track radiation to one part per trillion, perhaps there is a harmless isotope we can employ?
Mickjoebill