This kind of writing is not easy. Students in a couple of library class know this very well because they attempted to write rhopalic sentences. They did a great job, but ran into the same difficulties that I did with getting a great idea only to realize that the next word I wanted did not fit the rules.
Here are some of the sentences that students in grades four and five created in under 30 minutes, many with time left over to look for books they wanted to read.
With increasing/decreasing number of letters:
A no tow sign makes people quickly withdraw.
I am not good after dinner, Chicken Annelore.
I am the cool super person.
Why am I?
I am Jen Mood.
I am not nice.
With increasing/decreasing number of syllables.
Some person vomited Technicolors disastrously.
What lovely butterflies.
I played Mancala.
Kids-- skiing, snowboarding, outrageously extraordinary!
If you rearrange the sentences you can create some amazing poetry, especially if you stick in a couple of rhopalic sentences of your own. Let me know what you can create.