Deseronto has a good launch. The dock needs some repair but expect it to be fixed by opening weekend. Parking shouldn't be an issue.
Pay attention to the parking signs. The Town hired a new Bylaw enforcement company, so not sure what to expect in way of enforcement.
The mouth of the Napanee River is a hot spot for the first couple of weeks. Also the south shore of Mohawk Bay south into Long Reach is good.
Water depth is 12 to 17 ft. in this area. A lot of guy's fish around the submerged cable which is a little further south on Long Reach.
Deseronto to Hay Bay is 10.5 km and Picton Bay is another 5 km. It would take you maybe 15 minutes or less to run down to Picton Bay.
In Deseronto there's two restaurants on the main street a short walk from the ramp. "Griddle me this" and the United. There's also the old hotel called the Dock Side Inn. Was by the other day, might be closed.
Depending how busy the park is, you might not want to take up a spot at the dock for long. I wouldn't leave anything of value in the boat while your gone.
If your down Picton way the Picton Harbour Inn has the Lighthouse Restaurant which is online and shows breakfast and lunch until 1:30 pm.
There's dockage at the Inn. Scott Walcott who operates Bay of Quinte Charters owns the Inn. If you considering that. I'd call the Inn and check on docking for lunch.
http://www.pictonharbourinn.com/docks-at-the-inn.php 800-678-7906
If there's anything else you need, please feel free to email me.
Hope this helps and have a great fish.