An ad-lib is less risky than a joke with a set-up and a punchline because there is no observable set-up for a laugh and no awkward hang-time after the punchline.
Ad-libs are risky, though, in the sense that when you think on your feet you may come up with material that just doesn’t work.
Use ad-libs the safe way: Think up a few planned ad-libs (which clearly is as illogical and self-contradictory a term as the “mandatory option” a car salesman recently tried to talk me into, but so be it) and deploy them during your presentation.
You can probably look at the program or script for your presentation and envision situations that will arise that would lend themselves to a humorous remark. For example, I once emceed an event that had an awkward moment planned where two retirees would come to the stage and stand next to each other while they received an award. By bizarre coincidence, one was 6’6” and the other an inch or so taller.
I am of medium height, so I knew in advance the grouping would be visually odd, so I used the situation as fodder for a planned ad-lib. I decided that instead of ignoring it I would call attention to how awkward the situation was, and observe that I felt like I was surrounded by redwoods.
After a beat, and a very mild laugh, I would add a misdirection line…
I meant your AGE, but you’re tall, too.