By orally active you must mean sublingually. The acetate won't work when swallowed either, only dissolving / absorbing in your mouth and keeping it there for like > 15 minutes or nasal (or rectal) administration will remain as viable options.
Adding vinegar will allow the freebase to convert to the acetate salt which will be able to dissolve much better in polar solvents like water and alcohol. The advantage of alcohol and vinegar is also preservation/conservation but they need to have a certain minimum concentration. Best is to make the alcoholic portion 20% of the total volume or more. Excess of vinegar is unnecessary and not ideal as a preservative, it will also make it relatively nasty.
I don't think it's wise to try and lay blotter yourself. That kind of dosing method is sensitive to errors and drops are not an accurate volume to measure. Instead of a concentrated 5 mg/ml you can make it 1 mg/ml instead and use volumetric measurement with an oral syringe to measure doses to swoosh around in your mouth. Creating a concentrated liquid to administer intranasally is also possible but you should really do your homework on that kind of thing to make sure you are not overdosing.
It's safer to make it so that an average dose is 4 or 5 volumes administered by nose than trying to make it into 1 single unit. That way you can start lower. You can dilute a preparation as well to be able to gauge the strength of your preparation.