I also agree about getting a 26. It will cook about double what will fit on a 22.5.
They make a Smoke EZ for both the 22.5 and 26. That would add more options to your cooks.
Most of the offsets are made from recycled beer cans. If considering one do lots of research first. My brother had an older Brinkman given to him. It was better made than the newer ones. We did lots of work on it after doing lots of research. With 3/16 Tuner Plates, etc, etc we ended up with a better working smoker than when it was new. We ended up donating it back to the original owner.
My brother then added a Smoke EZ to one of his 22.5. Weber's. Now he has a great grill, and by adding the Smoke EZ his Weber is converted to a 22.5 WSM only better.