What I'm reading here though is those two things don't necessarily work together. If you've on a derive, you want to look open to new experiences, almost inviting them to happen. If you're on a GASM, don't you want to avoid notice, meaning looking as busy or natural as possible?
That depends on how legal or accepted the thing is that you're doing.
All a GASM is, is a Discordian call for help with a Golden Apple Seed Mission. For example, if your GASM would (partly) be along the lines of something Safari-esque, it's natural enough to get your surroundings involved.
On the other hand, I dunno if it's still strictly a Derive, if you're on a Golden Apple Seed
Mission, because the aimlessness is somewhat part of a Derive, isn't it?
Maybe not strictly, but in a practical sense, relating to the experience, I can't see much of a problem with putting up posters, stickering, handing out flyers, or even doing some kind of fun improv pranking going together with getting into unexpected adventures.