That's it. I managed to implement options for QLFits3, thanks to the fantastic help from the BetterZipQL developer (Thanks Robert!). 

It has been quite an interesting challenge! Now a tiny “config” app is bundled with the QL generator and is running un background, listening for some custom URL scheme whose content is formatted in such way it is transformed into key-value pair, which in turns is saved inside a pref file… 

Let me know if it works for you! The one-line installer:

curl -fsSL https://raw.github.com/onekiloparsec/QLFits/master/Scripts/install.sh | sh