A lot of people like the Portable panels, and having tilting systems, but I have to say that for myself, I have to agree with everything aboveOh, I have a different opinion.
A fixed solar panel on the roof is a fit and forget fix. You can ignore it year after year. Yes, you can align a portable panel to face the sun and get more output, but it's far easier, and just as cheap, to fit twice as big a panel flat on the roof instead
You see people setting up their portable panels, then a few hours later the sun has moved and the panels are in shade. Or they blew over in the wind
And even if you don't mind the faff of setting up and packing away, they are always at risk of theft or damage.
For me, one of the best things about having a motorhome is that when you arrive, you just put the handbrake on and the ignition off. No setting up needed.