Just adjust price points appropriately. Yea, will be easier Jan/Feb/Mar. Again, point is that objections have used Ret T as reason. Reg T does not apply to futures&futures options.Quote from optioncoach:
The underlying is not the same. Right now the NOV/DEC trade off the DEC future but the JAN cycle trades off the MAR future. As I found out it messes up the striaghtforward calculation.
I put one one recently and simply pushed the DEC EW out 15 points further OTM to hopefully offset the jump in premium from DEC to MAR but it makes modelling that much more difficult. I think it is easier to do when all 3 months are priced off the same underlying future.

