Skillchains aren´t that difficult anymore.
Here is a solution for the quickest way:
take a rallycar, drive it to the quarry.... go berserk. that´s all. jumps jumps jumps jumps jumps
if you wanna go real berserk: hoonigan focus, carskill upgrade and go berserk in the windmillpark. hit the gas and never stop it. i made 1000000 skillpoints there without any trouble