Mansell looks solid enough from what I've seen, but I'm fairly sure he'd be a trade I'd end up regretting because he's unlikely to stay in the side long enough to make much cash. No idea what I'll do if one of Clark or Highmore can't get back in.
If Vlaustin is out for 5 then I think it's a decent amount of games to generate a bit of cash, assuming he can score higher than 30s and 40s (averaged 75 in SANFL if that's any indication so not a bad base to work from albeit in a much weaker league).