I’ve done the half darkslide trick with 8x10” and it works perfectly. It’s a lightweight, compact, and inexpensive way to carry a second format in a large format kit, plus you get two shots on every sheet of film. 4x10” has a similar feel to 6x17cm, so after a period of shooting both I sold off my bulky 6x17cm expansion back for my 4x5”. The aluminum expansion back needs a sturdy camera, so I used it on my 4x5” Linhof Tech V, but the half darkslide has no special requirements, so I can carry it with my ultralight 8x10” Gowland Pocket View.