Layout problems when publishing

I am publishing a musical play, and the final score will be over 350 pages; while I have divided the score up into PDFs that are between 1 and 45 pages each, I am having trouble laying out some of the pages. Most of the songs come out just beautifully, but ensembles that keep shifting from a few voices to many give me lots of problems.

When there are combinations of solos/piano and large choral forces, sometimes museScore will relegate one or two measures on a page, then leave the rest of the page blank, and continue on the next page.

While I see why it happens, it looks terrible from a professional point of view, and I wish there were a way to move the measures around better, in order to maybe squeeze one and spread one to make two systems fit on a page instead of a tiny amount of score taking up a whole page.

What I tried to do was insert 'blank' measures (putting one note in a staff, then turning off visibility) so that the rest of the page is filled up, but that too looks unprofessional, having a page that is mostly blank staves.

I think I am taking advantage of all the tools available in the software, so far as 'omit blank staves' and stretching the individual bars however I can; but there are times when it simply doesn't work.

I am attaching my score that uses the blank staves -- if you can find a way to make it more compact and professional looking, I'd love it if you can tell me how to do it.

Also, please don't change the margins, as I need to have specific printable edges to go through Amazon's print system.

Thanks for any help you can be.