You should be able to find Kosher for Passover imitation vinegar (acetic acid) in smaller bottles although a lot more expensive than good old vinegar. Kosher supermarkets should carry it at this time of year. (You can find it on Amazon as well but very pricey.) IIRC from previous years, the supermarket price is in the $3. range for 32 ozs.
I don’t know how by much you dilute it, or how much you use for Yom Tov, but hopefully you can make it work.
There are also Kosher vegetable washes, but I’m not familiar with those.
Good luck!