I am familiar with the origin of the word premises as it relates to property, both land and structure (relayed here: Is "premises" always plural?). I want to know if there is an accpetable adjectival form.

So which of the following is most correct and which are acceptable?

1. Virtual events are less effective than on-premise.
2. Virtual events are less effective than on premise.
3. Virtual events are less effective than on-premises.

(I know that reforming the sentence so that it doesn't use an adjective would likely be best, but what is the runner up?)