I am doing 5 full A levels and already have 1 AS on top of this. Although I did not do them at the same time, my current grades are AS AABBC A level B
I did this because it is part of my school's protocol. It was not my choice. If universities ask, I will just state this. This should not be a problem for you, but I would worry about workload. I cope okay with 4, however I would be pushing it at 5