In my honest opinion, obby maulers are not fun. I recently ruined mine due to complete boredom whist pking.
There are very few people near your level, you are not fooling anyone hiding the maul, you will not get good loot, everyone that is near your level also has a maul, and it is terrible to train.
Obby maulers are only good at around 80+ strength.
But to train to 60, you may be looking at 13 hours or so. Remember to use a topaz machete and a glory or another amulet that gives a good accuracy bonus. You're not looking for strength bonus, as you want to hit more often. Also, get a warrior ring.