I would be careful. Scars can be much more sensitive to the sun and it could leave them looking ugly. Sunscreen will work in the future but I wouldn't put it on at 3 weeks pp. Maybe if you can cover the area? Wait, I didn't read the whole thing. I would think that would be fine
I’ve not asked the specific question on c sections, but when I had my boobs done, the surgeon told me very clearly to keep my scars out of the sun for at least a year, as it will affect their appearance as they heal and they’ll be more prominent. I still went on sun beds etc, I just covered the scars specifically. Sounds like your plan!
I mean, I don’t see why not except maybe getting in and out of the high flat bed. Maybe a stand up?