Yes, it'll do no harm! Be aware that you may find it more difficult, so be prepared to repeat weeks that you find hard, and look after your muscles properly as they will be working hard. 50g carbs is not much. I did a lot of walking when I was last on a VLCD and used to just run out of energy quite suddenly and would be very very shaky afterwards. I would probably go for half a shake fairly soon before you set out (it's hardly a heavy meal) and then another half afterwards and see how you feel on that.