We have done several 2-3 month trips and my thoughts on this are that we aren't going to go more than 20-30 miles without passing a Walmart, Target or other discount chain.
We have our regular pots and pans that stay in the RV, we have staples (flour, sugar, cornmeal, dried beans, eggs, milk and sodas) with us. I will usually purchase a couple of frozen bagged meals to fix when I am tired and don't really feel like cooking. I have one set of sheets/blankets for each bed and these will be washed along the way. If they need to be replaced, we replace then on the road.
We have not travelled in that direction...yet, so I have no recommendations.