I tried two options - first, I bought some Old Navy inexpensive (on sale) fleece pants (my surgery was October), I split those for about
15" at the outside seam at knee height on the catheter side leg. That was big enough that I could push through the empty and slightly folded Night Bag. Once the catheter was gone, we just stitched up the seam and I used them for walking pants.
Second was some Adidas "100G" nylon pants - snap up the full length of both legs on the outside seam. Generally considered "basketball pants".
You may find the basketball type pants in stock at a sporting goods store if there is a college/university in town. My local stores only did them as special order, so Adidas on-line was the alternative.
At home (indoors), I just wore a light bathrobe. With the bladder spasms, that was enough to deal with.