Hi there
I guess most of the good hints were already written, so this might be new or overlapping with someone elses suggestion.
As I understood, you were asking for advice for working alone (?) outside the dojo.
'Two- steps' is always something you can do at home or any other place. It might look boring, not changing, but practising it alot will show results later on.
Another thing is walking around the house always keeping your hands infront of you (helps you stay connected to your center). This will help you out later in not leaving your hands behind when you do different techniques (like Shionage, Iriminage...).
It's preferable to do this at home, outside people will look at you strangely !
I liked the idea of walking in crowded streets, I think it's great!
There is another thing that I learned from a totally different direction. It's the idea of walking in an 8 shaped pattern. There is a therapy for dislecsy in this fashion and it is said to help connect neurons in the brain, but also keep focus, concentration etc.
I'm writing this in a very unproffectional way, but the training itself, putting 2 chairs apart and walking around them in an 8 shape while concentating on a specific point is said to help.
I've been doing it, but not long enough to say if there's any difference, but it certainly can't hurt.
It's also a good way of training to move around obstacles, so it probably contributs something.
Hope this helped, and continue to enjoy Aikido!
Anat