Please help me out!

I’m wanting to separate the garden for the dog and my little girl to have half each as my little girl likes the garden and can’t currently have her toys down on the floor as the dog constantly marks his scent on absolutely everything 😂all her toys are currently up off the floor on the garden table but it’s not fair for her to Only be able to play with her toys in the garden when he’s inside. And I’m wanting to do a memorial planter box in the garden for my angel baby coming 12th September and I don’t want him constantly peeing/marking scent on it as it’s special to me.

Has anyone got any ideas on how I could separate the garden as shown in the picture below please

I do live in a rented property so can’t do anything permanent