Don't backpedal in the 10t. The only variable that will change the backpedaling performance is changing the chainline. The rear derailleur has no bearing on this, being placed after the cassette while backpedaling, it is no longer guiding your chain to the cassette. Your chain is skipping because nothing is guiding the chain off top of the front chainring to the top of the 10t cog while backpedaling. It is an extreme angle for the chain to take, and it wants to take a smaller angle, so with nothing to guide it out further, it catches on the next inner cog.
Solution is to not backpedal.