Thank you very much for your advice, Imafuji-sensei.
Indeed I find it much harder to maintain balance and make quick turns after striking in the sand. And I'm glad to know this will help me train that aspect of my kendo.
I'm eager to wear bogu and get as much time training with bogu as possible, so I guess I'll have to find an alternative place and divide my training, as I really don't want to be the responsible for sand in my dojo.
Thank you again, I will pay special attention to all the points you marked.