Checkout of orphan branch files into mainline worktree

Hi folks,

I have a repository where I maintain a project for a web site with a branch (disconnected from the mainline history) that contains some files (necessary only for a particular instance of a site) that don't intersect with others files in the main project. Since I don't want to use submodule and subtree I manage myself to this sequence of commands ("deploy" is the branch name of the mainline history and "index" of the --orphan branch) to checkout the index's files into the mainline files

git read-tree index && ( git ls-files --with-tree=index | git checkout-index --stdin ) && git read-tree deploy

Are there some other ways to do this? I'm crazy? are there side effects?

Thanks,
	Gianluca