Blue,
I have used Aspen for the stems on a stripper, and planned to use it for the gunwales on my current stripper project.
I'm not sure what the "numbers" are, but it is a semi-hard wood that is reasonably tough and/but also light. (I put 1,000 bf of it on the cabin ceiling so have a little working experience with it. Like other woods, specific boards can vary a lot as to weight and hardness.)
The only reason the current project isn't getting it is I could only find 8' boards and I don't want 2 splices.
Yes, it isn't very rot resistance, but on a stripper that isn't much of a issue. And the other hand, ash isn't very rot resistance either but lots of folks except it's use on canoes.
Other examples, birch also, in the woods, dosn't last long, but was often used for decks and other trim on canoes. And basswood was commonly used for all wood strip canoes, how long does basswood last when it is wet?
For a sealed construction, I wouldn't be afraid of using aspen. I've not sure I'd use it for unsealed construction like W/C except easily replaceable pieces like trim.
Dan