Both have a PCD of 5x112 dont they?
Dont see why they wouldnt fit with spacers at all but they'd need to be hefty if you work out the details which ive guessed tbh.
RS4 et45- 8.5j ?
RS3 et50- 8j?
Means the inner clearance is 53mm less and they'll sit 27mm further under the arch if i've used the calculator correctly.