Well, I don't know of any Weeknder doujinshi besides the ones you've already scanlated, or any more doujinshi by Wawon.

However--unlike Weekender, Wawon still has their website up, and if you scroll down on the side bar, you can see a comic section. Their just 4-koma type gag strips, but they might be fun to look at! :)

http://wawon.tobiiro.jp/pict/pict.htm