WebsterBikeMan

We're planning on something like 7-8 months as well. Not in the next year, but coming. I would think in terms of mail drops when it comes to both route maps and seasonal clothing. Don't know if that's possible in your case. Someone said that you need no more for a year than for a week, and I don't entirely agree. You can see a week's weather forecast and discard unnecessary clothing. But ideally you want to be wearing every scrap of clothing you own on the coldest evening/morning of your trip. If anything is leftover at that point you packed too much. The other thing to think about is how little you need in terms of spares (chains, tires, ...), and the extent to which you can arrange mail drops for these, as at this duration you're going to go through more than just lubes and tubes.

We are using Arkel TT84s (rear) and GT18s (front). This gives us more than the carrying capacity of a Bob, with less weight in the panniers themselves than the Bob. And we're the sort that like pockets and compartments, which resolves the Arkel/Ortlieb debate for us.

Your mention of toothbrush handles reminds me of a back-packer trick of sucking toothpaste into a straw so as to save the weight of the toothpaste tube. Not something that makes sense to me in a 7 month endeavour. In fact things like toothpaste and shampoo are a tough call - you want the smallest packages you feel you will be able to reliably replace before you need to go without for an extended period, since anything bigger is extra weight.

But toothbrush handles are unlikely to be a serious contributor to weight. More expensive to reduce but more effective are the tent, sleeping bags, clothing - most things you only need one, some bike clothes, two. Weigh every piece of clothing and if you have a choice between two items take the lighter weight one. Kitchen can add a lot, and has a fair amount of room for variation.