If you dont even wanna set anything on wattman, then best is to leave it as it is.
Cause spending on another cooler is not advisable. You need to do a lot of things just to make it work. You need to find ways to cool the vrms and VRAM sections with a proper heatsink.
The only problem with this RX480 is due to the heatsink cooling capacity is too small and hence you will need to do tuning of the card.
If you really do not wanna tune your card then i suggest, sell the card, get the GTX1060 which isn't gonna be cool either as Founders Edition card needs to tweak the fan settings to cool things down. Else you will have to get an AIB partner cards such as Asus, MSI, Sapphire, to come out with their own coolers.