When the meal gets larger, it will be as it can be very difficult for your snake to get around the feet while eating. Are your feeding rat hoppers? If not at 5 months old I would get your bp onto some rat hoppers at least.

If you feed FT (frozen then thawed): To help your bp go for the head, make sure once you have heated it, the head is warmer than the rest of the body (the same as if it were alive). You can do this by blasting it with the blow dryer for a few seconds or simply holding the lamp over the head. When you put the prey in, point the head toward the snake, just dont force it on him/her.

Overall it wont hurt your snake to eat it backwards but it will get harder.