Girls often do appreciate a guy approaching her. It all depends on the kind of energy he's giving off. If he's nervous, hiding his emotions and having a secret agenda, the girl will intuively feel that and be put off. If he's genuine and in his masculine precense, as well as being playful and light hearted, she'll also intuively feel that and be energetically drawn to those vibes. It all depends on the guy and the energy he's giving off. 

Fruits and nuts will not be enough to sustain you. You will be extremely hungry and quit.
It would be more reasonable to light-proof an entire bedroom plus attached bathroom, so you have more space to move around, sleep, and store food.
Right now I pretty much sleep in a pitch black light-proofed bedroom. All the windows and even the door is totally blocked with special thick curtains.
That would be the way to go about it.
Logistical planning for retreats is very important. You need to address all practical issues ahead of time so you can fully focus on the retreat without distraction.
You could even install a small fridge in your bedroom to hold pre-cut fruits, sandwiches, pasta salad, etc. You could stock up on beef jerky.