RevBec, I suspect my gap is/was in a different place. My gap was near the floor and went up about 5 inches. It was between the hallway wall board and the base of the shower......not in the shower.
I used good ol Elmer's white glue. Part of the kitchen sink and the pantry are across from our bathroom door. I couldn't move the shower base board to I applied pressure to the hall way wall. I used my bottle jack (laid it on it's side) and a 2 X 4 cut to make-up space and "jacked".
Kistler & Brenda
2002 Classic 25'
2003 Expedition EB 5.4L, AWD, AdvanceTrac Class IV hitch pkg. Reese dual cam/Prodigy