I have a grammar question for a story I m writing?

You need an apostrophe to show possession. Usually an apostrophe and "s" are added, but when the word already ends in an "s" the extra "s" sounds awkward.

It's time for John's bath.

It's time for Rufus' bath.

In the second example you are trying to use the apostrophe as a contraction and not use the word "is." It doesn't really work.

Rufus is too short to ride the roller coaster.

It's my understanding that with a person's name, an apostrophe would be added to the name - "Rufus' bath."

Rufus's bath. Many people would also accept "Rufus' bath" (with an apostrophe but without the extra "s") as being correct. The Chicago Manual of Style, though, which is used by many authors, publishers, and teachers, prefers the first way: add an apostrophe AND the extra "s", even for names that end in "s" like "Rufus."

And in your second example, the contraction of "Rufus is" would be "Rufus's"; there's no other way to write that one.

you can use smaller margins for that section. bring everything in an extra inch or so. a different, handwriting-looking font would also work.