Nice work, whereabouts are you heading? I live in Thousand Oaks, NW of L.A. Moved out here 12 months ago with work. If you are anywhere near drop me a line, we ride pretty much ALL the trails from West L.A to Santa Barbara, and there are lots !!
Now its warming up (It was 112 degrees at 18:30 this evening !!) we see Rattlers pretty much every week, saw a HUGE one a few weeks back just chillin in the middle of the trail!! Turantulas that will fit in your hand and Coyotes if you are out after dusk (but they are scared shitless most of the time) I have ridden with a few guys who carry a "Bite Kit" for snake bites, but its simply for giving you more time if you get bitten. Generally the big adult Rattles scarper very quickly, but its the babies that are the dangerous ones, as they cannot control the venom.
One thing I'd recommend is getting the BIGGEST Camelbak bladder you can carry, the biggest shocker for me was the heat and hydration!
If you want any help with anything my email is nathan dot thomas at technicolor dot com
Cheers