Planning any trips to Canada anytime soon? The Robertson (square drive) screw has been the standard here for years. Any hardware or reno centre will have more options than you can shake a stick at. Trumpet or bell head; metal, self-tap, wood, concrete, or speed threads; galvanized, coated, stainless, brass; 1/4" to 6". You name it, we got it. And with the way the Canadian dollar looks right now, you can get them for pennies on the dollar.
Oh, yeah, once spring hits we have really great camping up here too...
2011 Jayco X19H (purchased 2015)
2008 Jayco 1007 PUP (purchased new, traded for the X19)
2012 Chev Traverse LT with TP