Certainly is possible, but you would need to move the cleanout, the wye and 45s up so you could fit a fitting into that space as 2" is not enough space to install a fitting.
It would not hurt anything as you could at least install a sanitary tee fitting that has some flow direction to it
... compared to a cleanout tee as it is... this may lessen the backflow.
However, it wouldn't change that fact that you are attaching onto a kitchen sink drain line anyway...
That pipe is kitchen sink drain line EVEN UNDERGROUND
... so changing fitting to sanitary tee not bad, but not perfect solution.
The perfect solution, believe it or not, would be to install this drain into the underground piping at the toilet... or even at the lavatory pipe underground... but for now, as I said... I'd stick with what you have.. see how it works out.
You can always chop up the floor and connect into a larger drain pipe if need be later.
Glad to explain more if you decide to change that cleanout to a sanitary tee... let me know.