The foam idea would work and I did just that to all my Roombas and My Braava M6. This is what I used as it’s thinner and cut to fit:

https://www.amazon.com/gp/product/B08HV48WQV/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1

No way to get rid of or decrease the size of the no-go dock zone.