I've thought about this in the past, and I always first signal any fouls that are waived off, such as NY because the player in the RZ was onside.
Then signal the declined fouls, grouping offsetting fouls together, then lastly the accepted foul.
I had this situation in the summer, on a TV game, and I think I may have just verbalized that the BFR (actually the 15y variety) was "disregarded" without giving the decline signal. Then I gave the RTK signal.
I like your logic though for signalling the decline.