I'm not sure exactly how the -8 attachment differs from the -6 or -7, but I found it useful to remove the wing tanks as well as the flaps when I put the wings on my -6A. With the tanks off, you have a little better access to the cockpit area from outside the plane. The tank root attach is not critical at the initial install as you set sweep and incidence with the rear spar attachment. The tank attachment is a slip joint useful for supporting the weight of the tank and fuel but not for setting alignment of the wing; you can do it later.
Sometime after attaching my wings, I put the tanks on, made the connections to the fuselage plumbing and added the root attach and safetied it. Then I did my root fairings and assumed I was done. HA! I just recently had them off again because I found I had to isolate the resistive senders from AC ground for the BMA EFIS. While I was at it, I installed new gaskets and re-tested for leaks. On the silver lining side, it was suddenly easier to work on the cockpit wiring and plumbing; I should've just left them off until I was ready to plumb the fuel system to the engine.