I put an 'event' in the calendar on the last day of May (and monthly through to September if it proves of interest). It's a virtual event, there's no physical meet point, it's just in the calendar for interested parties to upload their participation photos for that month.
On the first of May (and next few months if taken up) I post a new thread giving you a theme or themes for the month. If you want to join in, you take photos of your bike and somewhere that fits the theme. I can't produce a list of places around the country that everyone will have opportunities to 'bag', so I give you the subject and you choose your own locations. Equally, I'll not be able to set points values for easy/hard targets, so use your imagination and find places that can earn you bonus points - you'll probably have to tell me where they are!
Two or three days into the new month (hopefully with a new challenge set) I will review the photos uploaded to the event and pick a winner.
GOLDEN RULES of rally challenges: obey all road/riding legislation, make sure that you and your bike are street-legal, do not put yourself or anyone else at risk by thoughtless parking just to get a picture, take breaks if heading out on a long ride, etc etc - you're all grown up boys and girls, you know the score
If you've never done a scatter rally you must surely have done a treasure hunt or poker run and this is the same kind of thing except that instead of giving you a list of places to go or things to collect I'll give you a theme and you choose your own places to fit. You go there, take a photo of your bike then post it on the event photo board.
Instead of deciding locations and points values in advance I'll award points somewhat arbitrarily (phew, thank goodness for spell check!) so you won't know if you've bagged a high score until I've spent some time going through all the photos.
This is just a bit of fun, don't go charging all over the country spending a fortune on fuel and cakes (unless you want to), but perhaps it will make you think of new places to go and give you an excuse (if you need one) to go on a bimble.
If you like the whole scatter challenge idea, you could do worse than looking up the one in the Events calendar on 17th June and coming along to that.