Vagrant synced_folder + composer

I have Windows Host for CentOS Guest VM that is running php-fpm + nginx + mysql using the following synced_folder in my vagrantfile:

Vagrant.configure('2') do |config|
config.vm.synced_folder '../sites/', '/srv/www/', type: "rsync",
rsync__args: [
      "--verbose", "--archive", "--delete", "-z", "--chmod=Du=rwx,Dgo=rx,Fu=rw,Fgo=r"

That has a documented limitation that rsync is one-way from host to guest. Which is fine, except for those times when I run composer update in the VM. My host PC files are then out of date and subsequent rsync will overwrite / delete.

However if I use the standard synced_folder equivalent nginx does not see the folder and I get 404 errors with permissions issues in the log. For comparison:

config.vm.synced_folder "../sites/", "/srv/www/", create: true,
mount_options: ["dmode=774,fmode=774"]

This seems like a rather common scenario that others would / should have encountered but nothing on the googles has shown me a solution yet. Suggestions?

Lieutenant Dan…You’ve got magic legs!