So if your making a g-mauler, focus on your strength and magic first of course, as that is what you will be using for the most part. Then when you have time/can afford it, you can work on getting 99 range aswell just to make your character that much stronger.
If you don't want to gain the hitpoints levels that you get from 99 ranged, just train it with SW. My friend does that and his character is an extremely low combat level on his g-mauler because he trained strength and range mostly at soul wars and alched to train his magic. Then he just adjusted his HP level afterwards to what he needed.