Will a simple RC filter work with my mechanical rotary encoder, or do I need a Schmitt trigger? I bought some incremental rotary encoders online  https://www.bourns.com/docs/Product-Datasheets/PEC12R.pdf

The spec sheet for those suggests a filter circuit for the outputs of the encoder that looks like this:



Adding that filter reduces, but doesn't eliminate, spurious signals from the encoder. I wanted to avoid adding Schmitt triggers or other solid state components since I don't have a lot of room left on my proto board for an IC, but I'm beginning to think I will have to add something with hysteresis since any filter that reduces jitter will also slow the rise time/fall time for the output of the encoder and keep it in the "gray area" between LOW and HIGH for a digital signal for too long.

Is there a way to wire these encoders and/or software that lets you read from them with simple passive filtering and/or software rather than adding something like a latch or Schmitt trigger for debouncing?
Having just chased a problem using a software based debounce for several days, what I'll add is that for the encoders I was using (green no-name Chinese ones), if you put 10mA though the contacts then the signal is a LOT better.   So change the 10k to 470 Ohms.  

Or if using 3.3V use 330 Ohms.  Solved all my problems.