I'm going to go with 3/32 front and back 'cause I've already got the chain and ring in that size.

I didn't know I had so much room for error! I put my ring on the inside of the spider last night and now it's within .5mm of the 42mm I have planned for the rear. Eventually I'm going to put a freewheel on the other side of the hub and the freewheel cog is ~1mm farther out. I was worried it wasn't going to work but looks like I'll be fine