Is it feasible to add a garbage disposal with this kitchen setup?
Prompted by K H's comment, I've looked at the specs of my dishwasher model and garbage disposal, and the sum of their current draw is over 15 A. Not a good idea to plug that into one 15 A circuit.
So irrespective of plumbing questions, a garbage disposal would require adding a new electric circuit in the kitchen, which would be too expensive given my planned renovation budget.