Just to add to the thought process of setting up training. If your dog is steady so you can do stand alone marks, then this scenario can work well. Can get multiple marks in with one duck or bumper. Have multiple gunners(white flag on a stick) in the field, sit the dog on the mat or line area. Walk out to one of the guns, throw a mark, verbally release the dog for the mark, dog picks up the bird, deliverers to you, then line the dog up to the mat and send it back. Teaching send back routine is very easy, Hillmann has some Youtube videos on it. When the dog is going back to the mat, you move to another gun. I do this with two dogs just alternate who goes first. Can do all sorts of training with minimal equipment. ABCD drills is great this way, you can also start moving immediately after the dog is sent, acts as a distraction, and hopefully the dog learns to focus on the mark not the thrower. Throw all 3 marks, one at a time, then run as a memory set up. That will really test memory. None of these are not my ideas but learned from others. Even hunt test dogs can use this technique, visible guns helps them identify certain scenarios, is hip pockets, converging marks, etc.
So don't get caught up and the need to always set up a ton of equipment.