fwd belly skin

I'm scratching my head as to how one is expected to rivet the 3 fore/aft stiffeners (F893s?) under the fwd cockpit floor while the exterior belly skin is in place. has anyone been lazy and used cherrymax or similar fasteners? the instructions for the F890/894 attach sequence seem a little convoluted. suggestions?

Rivet in bench first

The stiffeners are first riveted to the belly skin while on the bench (back riveting is best). Then rivet the belly skin to the fuselage and pop rivet the stiffeners to the floor skin. The drawings call out the correct rivets.

Here's a suggestion: somehow beef up the area between the exhaust ramp stiffeners and the sides of the ramp. This area is subject to a lot of "drumming" from the exhaust pulses. I diveloped cracks at the ends of the exhaust ramp stiffeners in only 50 or so hrs. and had to put a reinforcing patch on the outside. Works, but had I known it would have been much easier and smoother looking if the reinforcement had been inside. If I had it to do over again, I'd extend the stiffeners all the way to the sides of the ramp - and even double up on the ramp itself.