Fractional rextalisation with l-tartaric acid (the natural form) or, even better, the benzyl ester of the r form is not that hard. Usual you won’t lose more than 5-10% (of the right isomer). Biggest drawback is that you want to work in the 3-10g scale.
For the more speculative part. I look's like it's the r-isomer who make all the fun it's 2 times as strong as the racemate. In pikhal under DOB ½mg s-isomer have no effect and 1mg only might have an effect. My guess is that whatever the s-isomer is doing (dopamine system?) it's not very strong and might not bee worth the trouble to sweep out