Yellowstone- Gardiner Entrance

We (a friend and I) are headed down to Yellowstone in September and I was
going to go thru the Gardiner MT entrance as I have already been on the
Idaho side
Fortunately we have not had severe drought conditions
So the fish are not stressed - otherwise we would not go
(with my fingers tightly crossed) - We have not had a severe fire season.

Can anyone help w suggestions for campgrounds or other notable spots to see
and fish
I am taking my truck w a camper top and possibly my fishing dog - April a 7
mo old standard poodle.
I don't care if we camp in or near the Park

Any help or siggestions are greatly appreciated in advance.

Fred