Here's an example of a tripod like mount that works well on slopped roof decks.
http://www.3starinc.com/5_foot_tripo...oof_mount.html Most traditional tripods are intended for mounting at the roof peak only.
As far as testing reception before making any holes... a wood or fiberglass step ladder can be used to support the actual mast, or a temporary one. You also simply hold a 5' or 10' mast with and antenna clamped to it.
I use a grounding clamp (from the electrical dept. of the big box store) to connect the #10 AWG copper mast grounding wire to the mast. I use a corrosion resistant clamp, usually bronze, rated for outdoor exposure. If you have access to the electrical service ground rod, I would suggest you use a new clamp to connect the mast ground and the coax ground... Avoid disturbing the existing connection(s) to the ground rod if possible. Alternately, you can use a split-bolt type connector to clamp onto the electrical service grounding conductor, close to the ground rod.
http://forum.tvfool.com/showthread.php?t=901 (post #20 is a summary)