I always volunteer to be bumped, and invariably sell my bump vouchers, they go for ~ 50 cents on the dollar in the open market. I would not do so with FF miles themselves since they are directly from my account. -Somehow selling the voucher works in my mind's eye, at least.
As to using the voucher for a work-related trip and then being reimbursed, that is an awesome approach if your company permits it. Under that approach you wind up getting $1/$1 in USD. I know for certain that my company (a Fed agency, that is) would can someone on the spot for such activity in that you can only submit expenses for which you actually paid for. Still, if you folks in the open market can do so, this would be a great approach. -Might want to run it by your Co. first, though.