I also bought a bead roller to make flanges on joining panels. The panels are attached/rivetted to each other, so they will be flush fitted. Those panels that will be removable are bolted together.
For those I have used aluminium rivnuts and bolts.
I might add some beads onto the panels, but I'm not sure about that yet.
Using cleco pins makes it possible to finish the job on the bench.
I will install these panels permanently after I've bonded the body onto the subframe, so I have better access to bond and fibreglass the body to the frame where needed.
I will also install the back compartment after bonding the body and I have already fabricated those panels too.