Impressive. It looks like the cargo rails on the alucab are further out towards the edges of the roof than the mulgo. I have two 100 watt renogy flex panels mounted sideways and am debating adding one more. I started with flex panels to try to keep my height under control. I am hoping that I could deflate my tires and still fit into an 8' garage. I haven't tried yet but fully inflated I am about an inch too tall.
Anyhow, envious of all that power.
Flex panels are pricey or I might be tempted to put 2 400w panels up there like you've done, and wire them in series for more voltage "headroom" to charge my batteries in imperfect conditions.