The tripod idea on the roof peak is just fine. Radio Slack and other outlets sell a 3 foot tripod for cheap that will easily support a 10 foot mast & antenna with no guying. I have such a setup and have had numerous others including 5 foot triods, long masts and heavier antennas.
Stuff gets bolted to/through roofs all time. That's one use for ROOFING TAR (quart can available at any hardware or Lowes ect..) Always use roofing tar or some other suitable sealant when attaching something through a roof or yes it will be suceptable to leaks. I use the tar, never had a leak. Apply the sealant both underneath the tripod legs and all over the top of them when done.
Do not use nails. Use course threaded heavy wood bolts. The type with a hex head that you will have to drive in with a socket & ratchet. Also available anywhere.
As always, for VHF & up, use high quality, low-loss, 100% shielded coax. Use coax sealant "putty tape" around the connector where the coax attaxhes to the antenna to keep rainwater out.
good luck