I just took her normal potty in a bag the first couple of times as it was what she was comfortable with. Plenty of nappy bags and wipes to clean up any mess. Until she was happy to use her carry potty
I took her normal potty in the car for emergencies but otherwise used the toilets at my destination.
We use a 'my carry potty' and have a stick on seat that folds up in my bag x you can try holding her on the toilet