The photo of the Epsilon in the built up stage & without covering at the CA Models website shows it to be very similar to the Widebody. A tunnel looks to be difficult, but not impossible. It would depend on your bashing skills and the main gear that seems more mid plane on the Epsilon than Widebodys. I have the 40 and a friend has the 60. The 60 uses 4 wing bolts and my 40 uses 2 and 2 dowels on the leading edge. I would guess that you will have 4 hard points on the Epsilon for the wing. The wings have a pan box underneath that you build up on the wing bottom. A pipe tunnel would be easy there, and maybe under the main gear attaching point. The gear is where you would have to be creative with a tunnel. I think it could be done the more I think about it, but you will have to spend a little time planning it out.