Kootenai National Forest would be the best area to cross and best at night to cross the border then make your way to Yahk bc and have your friend pick you up from there. bring some bear mace just in case, don't light any fires close to the border unless you use a gasifier soup can stove and only during the day or under thick trees at night. if anyone asks just say you are backpacking the national forest and if for some reason ( i highly doubt it will happen) you do get busted trying to cross just say you got turned around and thought you were heading back south. you could follow South Fork Hawkins Creek so you will have water and water for food. you could also bring a 3600 calorie bar. but i'd suggest doing it very soon due to the snow and be careful because the weather in mountains can change very fast. look at a topographic map to plan it out to best fit your fitness levels. never walk on top of large hills( peaks) walk about 500ft or more below them to avoid being seen with binoculars, planes etc. walking on peaks you make you seen for miles.