I wouldn't feed her before the move, it will be stressful and you might risk a regurgitation, even if in 4 days I wouldn't risk the extra stress. I would say that using a sack would be a safer way to transport her but unless you will be holding onto her I would have her in the sack but put the sack in a tub so that she is secure, that way you can also put some sort of heat mat to keep her warm if its a longer trip/drive.
When I take my adult male bp (almost 4 years) to the vet or anywhere else I put him in a rabbit carrier that I got from petco and I put a blanket, a hothands hand warmer (in a custom cloth pocket I made so he wouldn't be in direct contact (even then I always bring the temp gun with so I can make sure it isn't too hot for him), and his emotional support sock monkey (it's not an actual emotional support but he is pretty obsessed with the thing and carries it around by wrapping his tail around it). It has a mesh pocket so he can look around if he wishes but otherwise he can stay hidden and secure the whole way there. It's a transporting method I recommend even if it is sometimes described as being "extra" since he could just go in a sack.