Cut all pieces from the cutting list. It will take some planning to make all of the 90° cuts, reset your saw & then cut the 45° pieces. It will be nesessary to use an angle grinder or bench grinder to debur & bevel the cut ends before you start to assemble. One of the most time-consuming jobs is making the tie-down braces (See 4th pic). Mark & drill all of the required holes for eye bolts, etc.
For the eye-bolt tie downs on the top of the rack, I used a decorative end cap for wrought iron fences. I drilled a hole through the center & welded the nut from an e-bolt underneath. Later I inserted the end cap into the top rail & welded it permanantly in place. In hind-site, it would have been easier & cheaper to bend & weld a loop of steel rod or flat bar to make these tie-down points.