I have been delighted with the Antennas Direct EU385CF UHF/VHF Antenna Combiner. It mounts with no hassle, and protects the connections from the weather.
http://www.amazon.com/Antennas-Direc...f+vhf+combiner
I've been fairly comfortable using wall or gable brackets with a 10' section of 1 3/8" OD mast. I have generally put about 7' of mast above the top mounting clamp, leaving about 3' between the upper and lower brackets. Never any failure even after hurricane strength storms.
I've always guyed masts that have more than one section.
A preamp such as the Winegard HDP-269 or Channel Master CM-7778 would drive a 4-way splitter and over 100' of coax with power to spare.