DO NOT feed in another enclosure. This peeves me and I do not know who started this "urban myth". Removing an animal to feed it subjects it to more stress and also exposes the keeper to possible SFE (stupid feeding errors). You should be able to feed any snake in its own enclosure without any problems. I have raised ball pythons for over 15years on aspen, newspaper and astro turf without any problems and I fed them in their own enclosures without problems as well as many other species of snakes. I suspect the rumor of feeding in another cage started with someone who was communally keeping snakes (more than one per enclosure to avoid accidents. Since you should not house snakes together other than during breeding, you should never have to remove to another enclosure.
Impaction is caused by many factors such as dehydration, overly large undigestible matter and suboptimal temperatures. Aspen taken in small quantities (relative to size of snake) pass through their system fine. You need to be aware of the frequency of the bedding ingested, but for the most part, they should not be shoveling it in while eating the prey. I keep hatchlings, subadults and adults on aspen shavings or Sani-chip with no problems. When you take a look at the size of their fecal discharge you will understand what it takes to block them up. Sorry for the rant, it is just a pet peeve of mine.