Trailing Grand Summaries are designed to "close up" the blank space and appear after the last record in the Body. That may not be what you want, bit it is what it was designed to do.
You could make this info appear at the bottom of the title page by putting it in a title footer.
You could put it in the footer using a calculation field or fields that are empty if Get ( RecordNumber ) does not equal Get ( FoundSet ) . The two values are the same only for the last record. But since fields in the footer can't be set to "slide up and resize", the space allocated for this info would be present on every page even if there is nothing showing so I have my doubts that would work for you.
The final thought that comes to mind is that you might be able to add in some special blank records after the last real record to "pad" the page such that your trailing summary shows at the bottom of your page. You might be able to use a script to add and remove such records if the space taken up by each record in the body is the same fairly easily. It's still possible with sliding fields, but the process get's really complicated and takes a special script that previews your report repeatedly until it get's the right stuff in place for your report.