Oakley will pee in the middle of the road or anywhere really but pooping is a whole different story…walking is the only way and he seems to do it in the same spots on our walks.. If the wind so much as sways it will deter him... In the cold he just flat out refuses to go! It is a basenji thing
Take it REALLY REALLY slowly. Be sure to make good things happen when they are together and getting along. It took me 7 months to get my 4 yr old basenji rescue (who has a very high prey drive) to coexist with an old cat. If there is a bad experience, it can set everything back months, so be very careful to set up good experiences and avoid bad experiences.
but I'm aware that extra weight isn't good for the breed,
I think that the issue with the added weight is related to her age. Once she is fully grown (12-18 months?) she should be able to carry some supplies: a baggy of kibble, a typical water bottle.... Things you might want on hand if you were going to go for a hike in the woods. Just let her grow up a bit first so that her muscles and bones are strong enough.