As per the title, whilst it's possible to design a symmetric fatbike rear using a 170mm OLD rear hub... there's no love for a fatbike design using an offset (+35mm to driveside) using a 135mm OLD rear hub. Or maybe some other width hub, eg: 145mm tandem or 150mm DH with 25mm and 20mm offset, respectively.
A manual work-around (for a 135mm OLD hub) would be 170mm rear to get the driveside mitres and a 100mm rear to get the non-driveside mitres. Always runs the risk of screwing something up(!!) and not possible to get an "over view" from the auxiliary views of whether the rear-end design fits together properly.
This and already requested tandem bicycle friendly BikeCAD... probably can see where a little project is going. Nag nag nag. ;)