I should have made it clearer. I'm running a 15mm spacer on the rear with a 9.5" wide Jupiter, offset 31mm for a net 16mm offset. I'm running a 20mm spacer on the front, 8.5" wide Jupiter with 49mm offset for a net 29mm offset.
Using 10mm spacers will take up 10mm of the original thread on your hubs. I wouldn't risk that.
15mm is the least you can go with a bolt on, hub centric spacer. What I bought below.
H&R Trak+ 20mm DRM Wheel Adapter Bolt 5/108 Center Bore 63.3 Stud Thread 12x1.5 ebay
MISHIMOTO 15mm SPACERS MMWS-006-150BK 5X108, 63.3/4, 12X1.5 AMAZON HGA Performance
The Aleutians are later model wheels and the rears are for cars with a wider rear track than the 07 XKR. A standard 46mm offset needs a 20mm spacer to get to the 26mm offset of the Senta which IMO has a decent stance from the factory. But as I said previously, at least one gentleman in the UK is running 20mm spacers front and 15mm spacers rear on Sentas and it looks right. Video on YouTube. When the car gets back from the detail shop, I'll take and post pictures.