Just go with what you have. Make sure to keep the pressure high in back. If it gets low I'm guessing you will pinch flat. I would suggest picking up a 28mm tire for a backup. If you do have lots of problems with rear flats....throw it on the back. 25mm up front with a 28mm out back should be fine.
Of course this isn't ideal..... but I tour on 28's after having done thousands of miles on 32mm.... Never again. Love the 28mm so much more. YMMV.
I'm not really heavy either. Don't know what your weight is? That can have adverse effects on my suggestion above.
Your wheels should be fine as well... Just try and keep your load as light as possible.... easier said than done sometimes...
Best of all... get going and have an experience of a lifetime!! Stop in at the library and give us an update when you can.