Afternoon sun will be fine. Many people grow successfully in 5-gallon buckets. Others have recommended (and I recently started using) Rubbermaid "totes" - either the 14-gallon or 18-gallon sizes. Put plenty of holes at the bottom and perhaps along the sides near the bottom, fill with soil, and plant.

If you think you will have a squirrel problem, you could either spray the plant with a deterrant (like hot pepper spray or equivalent) or perhaps cover the plant with some netting that is secured at the bottom.

You might be surprised that you CAN grow things well - sometimes it might not seem true, but you'll often find that it wasn't your fault but that of some adverse conditions (not enough sun or too much sun, too dry or too wet, too windy/not enough air circulation, bad soil, etc) you were forced to grow in. :-)

I only get one hour of sun in the morning.. and a few hours in the afternoon... and i have pesky squirrels digging around in the pots... last year i grew my first pot of grape tomatoes... they were awesome! i didnt need too much sun, .. they were a great treat to eat everyday after work... Im sure if i had better conditions i would have had more, but it wasnt bad for my first time.... good luck!