Dippry, id keep the rear offset but go 9J, go 8.5J for the front with a -20 offset
Using 15x8 -4 as a guide which sit sweet, the front will stick out 22mm more to fill the 25mm guard, the rear an extra 34mm for the 35mm guard
So front - 8.5J -20
rear - 9J -25
should sit mint, no spacers