@MrKABC, I was at the same decision point as you a few months ago. I have 800w up on the roof and at 38ft long, I do have room to double it. My wattage production has been a max of about 66% in summer and only about 50% as we approach winter.
As has been discussed, angling panels provides a huge bang for the buck. After a lot of overthinking, the route I am going for now is a portable/ground approach for additional wattage. I bought some thin/light/flexible panels (350w worth), a cheap PWM charger (for now). That way I get around the issue of a fully shaded site, I can angle directly at the sun and move them from shade if needed. Being a thin and flexible model, they are easy to store as well.
Yes, that is more work to setup/store but if at one site for a week I can live with that. Even at 50% 'efficiency' of the existing roof panels, it obviously maintains batteries in storage, and during travel they can fully power the rig (barely thanks to the 320 watts of the fridge) so I don't NEED more on the roof during those times. Then when living in it the portable panels add to the system and can cover the added demand.
I wrote a post a month or so ago about how I modified the Furrion solar input port to accommodate more amperage and use it for 'loads' as well.
I just thought I'd throw my approach out there as an additional option to consider.
Bryan & Julie
2020 Outback 341RD
2018 Ram 2500 6.7L Cummins Turbo Diesel