The best way that I can think of would be to print something that will surely spill over the boundaries and see what happens. Most printer drivers will return an error if you try that and you should get some indication of what will work. Try setting your margins to 1.8 inch (0.125) all the way around and you should get the message to change the document.
You may need a fairly long document in order to make sure that you go over to limit o the bottom margin. If you don't have anything handy, just grab something off the 'net, like the declaration of independence or some long article out of wikipedia (the history of sexualty ought to be plenty long for that purpose).
Then once you know what your true margins are, you can print your pics to that size. But remember that while you will probably have no trouble finding 8.5x11 frames, that is not a standard size for photographs (4x5 or 8x10 are standard) so you shold expect to have a bit to shave off the pic, unless you stretch it to fit.
And please do not stretch your pics dude. Not that you would but i have seen a few people who are obsessed with the idea that all pics must perfectly fit the place they are going. We had someone like that doing our company newsletter a while back and the results never looked like the person the pic was of.