Dorter Trade is the first time the Fur Shop *cough* *cough* I mean the uh... Warden's Office first appears, in essence the second sidequest (Boomkick) can be done, but it would require you buying the ticket prize from the Warden's Office, to bring up a new screen that could sneak in the conditions for the event (ala, Deep Dungeon and Beowulf).
Now as for yours PX it would need an event instruction at the end of Boomkick's quest to know that there's another sidequest at Dorter. Also there is... really no reason to be using Dorter Trade explicitly, there will be more sidequests then Bounties. I'll try to include a Treasure Hunting quest (I have a rather sizable one planned for late chapter 3), as well as some protection missions along with Timed Missions, now to get to Cheetah's question...
You recall the original plans for the Bar events we spoke of the other day? Well, it's a very similar concept, low speed and when that unit's turn comes up the battle ends, immediately, through a midbattle event. Simple as that. So yes, that idea you mentioned can indeed be done Cheetah.
Also fellows, keep in mind, that you can place sidequests anywhere you'd like on the map, while the main quest is (because it's already written...) following the normal path, these sidequests can occur anywhere one wishes it to be so.