Honestly, I personally can't stand Aspen, especially for BPs and similar species, or any species with specific humidity needs. I only use it for my Hognose because he loves to burrow and it holds his tunnels.
You're much better off with a coco coir substrate. I use a blend of Eco Earth and ReptiBark. I've been using it for years. It holds humidity well, spot cleans easily, looks naturalistic and there aren't any big chunks I'm worried about the snakes eating.