I don't think you'll need much of a touring plan. What part of June are you going in? Much will depend on if you are going before or after local schools get out for summer. Yes, doable in a day.
Regardless of when you are going, plan an arriving before park opening so you'll be ready to enter as soon as they open. Do the most popular rides first and then when it starts to get busier you can take that time to visit the older parts of Knott's that many overlook. Check out the graveyard and school house. Ride the stagecoach and train. Walk around Ghost Town.
If you want to eat at Mrs. Knott's I would go a little before or after lunch or dinner times so as not to wait to long. Like I said, we do the Chicken To Go but eating in the original restaurant it part of Knott's history.
What I like to do, if spending the day, is have chicken for lunch and then eat at Claim Jumper (across La Palma, at the corner of Beach and La Palma) for dinner. They have some of the best food-and huge servings-easily shareable.

You can walk there from Knott's. Oh, here's a picture of one of their amazing desserts. The I Declair. Sometimes we get this in lieu of dinner. Big enough to share with the whole table!
They have great kid's meals too!
Choice of sides, my DD10 picked apples/caramel and mandarin oranges as yer 2 sides. All meals come with an apple.
Another nice choice, nearby, is Fat Burger. Located on Beach, just to the East of Knott's. Good burgers.