What model of Mule did you look at? I'm 5'11 and one of the reasons I liked the Mule over the other brands was how easy it was to get in and out of it.
My 84 year old mom drives it almost daily and she has shrunk down to about 5'2. She has no issues with the seat, or getting in and out of it. One of the things that she loves to do is drive around the place after a storm and pick up branches that have fallen down. Then haul them to the burn pile. Mom never stops cleaning up the place, it makes her happy. Before I bought the Mule, she pulled a wagon around to clean up everything.
It's a 2011 4010 TransMule 4x4 that I bought brand new. The picture is right after I bought it, and before I bought the roof for it.
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And this was her pulling a branch to the burn pile that was too big to pick up. She gets mad at me if I do it for her, so now I just take video of her when I catch her doing something like this.