!!!WARNING: The statements below are not endorsed by the board management (or most anybody else here)!!!
Bent rear axles CAN be a valid method of building a well-aligned rail-guided car. It is true that they do require re-alignment whenever removed, but with the proper techniques and setup, this alignment can be accomplished in under five minutes.
From my personal point-of-view, deciding bent vs straight depends on a lot of factors. If you plan to build a lot of cars and you are using premium aftermarket stainless steel axles, I think straight axles makes a lot of sense. If you're running a single car in a cub race using stock axles (and you don't plan to be building more than a few cars a year), bent starts to seem more attractive to me.
So, without turning this thread into a bent-vs-straight war, I'll just say that techniques exist for accurate alignment with bent rear axles, and if you want to go this route, I'm happy to help out.
I would personally not attempt to run cambered rears by inserting straight axles into the slots. If you wish to drill your own holes, you definitely want some kind of jig to help you do it straight, because even a small amount of toe will destroy your speed. If you have a drill press, you can purchase and employ The Block. If you lack a press, you can use a hand-drill jig, like the Silver Bullet Pro.
You can also try some hacked-up methods, like
using a Revell guide with inserted pin to add camber. Tricky, but some have reported success at the Scout-level.
Of course, you can always just order a block with the rear holes pre-drilled, which might make sense for a single-car run, too.