Hi AlanMc:

In anothers programs -AutoCAD, Rhino...-, I use always layers (sometimes too much), and I like always to keep all the auxiliar lines in their layers. I usually don´t erase nothing.
In this case, I only can to manage the hide feature, for an easiest way of work. But I have to recognize that it is a tedious job, because I must to look for the auxiliar lines or objects and select them. Finally, if the draw is finished, I made a copy and I erase all the auxiliar lines (for render, layouts or share a lighter file), but always keeping the original model with all the objects.
Anyway this model is not complicated, because It is absolutely symetrical, and objects like the wheel (more complex and heavies), are mirroed and copied in the last step. :-)
About to manage some files, I´m not used to draw in those way, but I think that it is the best way in the complex models.
Sorry for this boring speech :-)
Bye!
David