Just a thought, I was taught to play classical guitar as a kid and translated this to the bass, the classical note fingering and not using my thumb to play with but as support on the back of the neck, But, there are no real rules, sometimes I only use my left hand and not my right, sometimes my thumb slides over if I feel like it,often my right forearm kinda holds the bass body to me and the neck is just there in space with my left hand free to move where ever, however, the bass is hanging off you via a strap so techicnally your not 'holding the neck', this will only slow or labour your playing, it should be effortless and balanced, weather you wear it high a la mark king or real low, its an ergonomic thing for efficency, however I realise image goes a long way for many, but that may be stopping technical advancement.
all the best guys...