I've driven several routes from Cherry Grove out to the coast when exploring in our Jeep a few years ago (I miss that Jeep)... The routes I took started off with pavement but always devolved into hard pack with occational new layers of loose gravel covering rutted areas. Get a really good hard copy map of the TSF - look for one with all the 4x4 trails. The roads criss-cross all over back there and one could get turned around in a hurry if you're not careful - there are very few road signs just forks splitting off here and there.
Don't relie on a solid GPS signal either. The pine needles are just the right length to play havic with reception for the GPS and most 2-way radios. Cel signals are non-existant roughly 1/3 of the way into the coastal range.
Keep your head up and ears open, because this is cougar country. Don'tsweat the bears -they will keep their distance. Cougars - mostly the young males - may see you as a possible snack. We've seen more and more cougars every year. Acouple years ago, two young (teens) cougars walked through our camp between the tent and the fire pit. Never had an issue with the coyotes - except at dusk but you should be out of the woods long before sun down.
Check with rangers as to the conditions up there before you go find out if all the snow is gone from the high points of your route.
Bring a camera because it is spectacular and the views are incredible. If you're quiet and observant, you will see wildlife.