Take your point about not over-extending but wouldn't you like a page or two and a link? It seems a shame not to if the space is there.
"Before you put the petition online you might want to think about membership and similar stuff. Free membership means lots will join, and then give you the task of sending them updates etc."
Not sure what you're advising. Are you saying a membership is a good idea or not? And of what - a Silbury Movement or Heritage Action?