The Puffin uses 170mm rear spacing, which means a Rohloff won't fit easily. However the good people at Salsa Cycles make an adapter for their 170mm back ended Mukluk. That adapter fits with no interference with the frame at all, overall seems very solid. I don't see any reason a Rohloff hub wouldn't work - with the following requirements;
- QR version
- laced to a rim with offset spoke holes to get the 17.5mm offset and retain some spoke triangulation
- skewer suitable for a 170mm hub
- speedbone or similar brake adapter to deal with the hub torque.
An Alfine won't fit in this adapter due to both the length and diameter of the axle.
The only other IGH possiblity is a 3 speed 170mm hub which is available from Sturmey Archer.