My FVC roof rack has a usable width of 57.3" whereas most 200W solar panels are an inch or so longer. No worries, just orient them different. Thought top-mount was too high and flush-mount wouldn't allow more support in the middle. Decided on bottom-mount so spare cross-beams would support panels in the middle since they were attached on ends. Good luck trying to align t-nuts for a blind attempt to insert bolts from the bottom. Solution: Set your phone on the van roof in selfie mode. You can now see when t-nuts are aligned and easily insert bolts. 600W on roof of Transit 148". Two Renogy 200W and two Rich Solar 100W thin panels on either side of Maxxair fan leaves room for vents. Specs match closely giving 597W output wired in series/parallel.