pro install and 35% sounds best for you as its the safe spot on your concern. but think about what color your interior is as well. my tan interior shows more behind a 20% film compared to my buddies black interior with 20%.
i live in nor cal and have 20% front/5% back for a year now. and davidfre21 is somewhat correct. i was pulled for a red light and the officer cited me for 35% tint up front as well. after fixing it and all that fun stuff, i went w/20%, obeyed traffic laws kept my driving clean. police have seen me with my tint and never bothered to tag me.
50% - can fully see you in the car during day. little harder to see at night.
35% - can still see you in the car during day, but hard at some lighting angles at night
20% - semi dark during day, still visiable. hard to see at night, must be under lighting to see whose inside. this is closest to what factory SUVs/Trucks use on the back windows on modern cars.
5%/limo - difficult to see during day and wont be able to see at night unless you have direct light.
hope that helps.