Rather than having a spoiler period, preventing discussions about the question, how about something like the "spoiler" tag that many forums have? For phpBB there is a plugin IIRC so this would be nice to have. E.g.:
"<clarifying question>.
Also here's my solution:
[spoiler] code [/spoiler]"
Spoiler period
Re: Spoiler period
Plausible. More important, we need to get these things organized again.