You don't need a ladder to get on the strut of a 172. There's a step on the side of the nose and a step on the strut. You only need one for the 177 and bigger Cessnas.
The step and handle kit was an optional extra on the strutted Cessnas. Most didn't opt for it. Don't climb on the strut unless it has the step.
...the placards on the 172 say to avoid slips with the flaps down. It's not a huge deal.
Best to stick with the placards. The effect of airflow over the tail varies with loading and speed. Sideslipping can also affect the ASI reading. On poorly maintained examples, it can also push the flaps sideways far enough to restrict the ailerons.
With so much flap, it's hard to imagine a situation where you would need to sideslip.
MJ
