The grace-note answer is the right answer to your question as you posed it, but your approach isn't as wrong as you think.
There are times when a composer explicitly does not want grace notes, but actually does something like what you have here. The composer may do this for a few reasons. Perhaps, the composer doesn't want to de-emphasize the structural importance of the notes (which grace notes do), or just wants to emphasize that the rhythms must be precise. In both of these cases, the grace notes will get explicitly written out.
This is also exactly the sort of situation where multiple dots are used (and warranted). We are at the end of a measure, and we are just filling in space for the last two 128th notes. So, rather than using a dotted 8th followed by a dotted 32nd, you would normally use a triple-dotted eighth rest.
"What?" I hear you cry. "Triple-dotted notes?"
Multiple dots are usually avoided because they are confusing, but when they are used just before the end of a measure with some very small notes, they actually trigger a mental shortcut for strong readers.
A multitude of dots redirect the attention of a competent reader away from the rest itself, and tells the reader to just calculate the duration of the final notes by subtracting the final notes from the time of the next downbeat instead of by counting forward from the previous downbeat. Sometimes, the first technique is easier, and having many dots is a way to let a professional level sight-reader quickly know that that is the best approach.