Since Los Santos is based on LA why aren't there any avenues for legal cannabis jobs in the city? In real life LA cannabis is 100% legalized and there are licensed growers and dispensaries.
My idea would be to add cannabis licenses to the department of licensing so people could legally grow and posses cannabis. This ideally would also allow license holders to also wholesale their cannabis at the several dispensaries already in Los Santos. For balance the license could be in the range of 200k and wholesaling would obviously yield less money per unit of cannabis than street dealing (which should remain illegal). Also, if license holders are found illegally selling their cannabis to locals they should lose their cannabis license and fine them or whatever you think is balanced.