Appropriate tool for measuring longer warps
Any time you dress your loom (put the warp threads on) via the indirect warping method (measure out your warp via a warping mill or board), you don't need to measure out all your warp threads together. If you are doing a project with 160 ends, you can use a warping mill or board to measure out two groups of 80 ends each, and put them on the loom one at a time. Here is a link to a YouTube video that shows a good way to store warp until you are ready to put it on your loom: https://www.youtube.com/watch?v=VQ1qNeSYBxs (You can also go to your favorite search engine and search for "how to warp chain" and find similar resources.)

A custom made warping board with extra long pegs sounds like it would be a great thing to have, but if you already have a mill or board, measuring out your warp in smaller groups is one way to make do.