If you are worried about the weight put a bit less fuel in. I bet you cant tell the difference between a full tank of gas and a nearly empty one!
I know I'm sad, but I've always been able to tell from full tank to empty, same as when I've got a passenger or being on my own; everything feels just a bit more 'spongy'.
You've got me started now...
Petrol weight 1 Litre = 0.711kg (at 60 deg F)
12.1 gallon (55L) full tank... 0.711 * 55 = 39 KG
6.05 gallon (27.5L) half tank... 0.711 * 27.5 = 19.5 KG
3.025 gallon (13.75) quarter tank... 0.711 * 13.75 = 9.7765 KG
The Mk6 calipers add about 10KG to sprung mass on the rear axle over the Mk5, so about the equivalent to an extra quarter tank of fuel; for no advantage, they are the same piston size and pressure.