you will need git to merge your content. if database is the problem you can host the database on a server which can be accessed by the designer than set the database on the laravel app to use that connection.

Old school method: Get a cheap shared host (ie, digital ocean) setup your laravel application let developer do his thing on your cheapy host pay developer download changes and ftp to your primary hosting service make setup changes for the new host delete cheapy host site

Using github means that you will have to pay attention to everything, like pulling his commits and what not. By doing it the old fashioned way, you just need to check out the work. The developer will still need a way to develop for your laravel application which homestead makes really easy.

Be aware that you will more than likely want a private "paid" github repository or get the free one at bitbucket.

Github / Bickbucket is pretty easy if you are familiar with them.