Well, I would first try to avoid the situation, but sometimes plans do fail.
But I would
not use a stop-loss order, for the reasons I mentioned. That would be the last thing I would do (hmmm... no, not even then, I did say "never", and I meant it!). Set them too close, and you really risk normal variation taking you out at a low. Set them too deep, and you don't have that much protection and you still run the risk of selling low on a dip.
This is a kind of forced market timing question, so I might just take a 'gut feel' of how I felt. I don't think OP mentioned a $ figure, but it sounds like a few tens of thousands, it's not like their entire portfolio is at short term risk, just this amount. So it's not life/death. If the market tanked, you'd have to sell a few more shares, maybe more than a few. If I was worried about the market being peaky, I'd either sell now and keep it in cash, or buy puts if they were cheap enough.
You know what, since this type of 'forced sale' is expected to be a very rare occurrence in this scenario (unplanned and all), I think that there would be too few 'spins of the wheel' to consider what a market does on average. So I probably would sell now, or buy puts, just to avoid whatever emotional stress might occur if the market went against me. The difference when you do this each year for normal withdraws, you have many 'spins', so it should average out.
But, just in case I wasn't clear....
.... I would
not place a stop-loss order.
-ERD50
PS: no stop-loss orders