Yeah, and lunging is good for that! I am a big fan of lunging as a training tool. I'll show some of the pictures of how I do it... just for conversation fodder :~)
You can do anything on the lunge that you can do under saddle. For training in precision I like to use double reins and a circingle. It best replicates the cues you'd use riding.
You mentioned the hassle of having to go somewhere else to use the round pen... You can do it without a round pen. The round pen makes it easier, they're less tempted to hang on the line, and they're less likely to just get confused and turn and face you, but it's doable, and getting there is good training time too.
Here's Cyn when we got her, she was round pen trained, we think, and she exhibited both common lunging problems... hanging on the line, and stopping to face us when she got flustered.
We solved it with double reins... You can enforce the circle by having an outside and inside rein to steer her with, run through the loops of the circingle to a snaffle bit.
ecurbh, though, found the line management issue somewhat daunting. :~)
But once you can get all that figured out, you can really to a lot with them this way, including figure eights, backing up, and changes of direction.
I also do work with trotting poles, which is probably not good with a gaited, but you could set up some kind of trail or gymnastic obstacle, just to give them something interesting to think about if they're bored.
Here's Bay, doing trotting poles, and a small jump built from the same poles... The diagonal wings help keep them from skirting off the sides of the jump.
