Zip-tie mount for Anker 3-Port USB 3.0 HUB with 10/100/1000 Gigabit Ethernet Converter [Amazon affiliate link - not available?]. Use wood screws to attach holder, then secure hub with zip-ties.

Would recommend this hub, but unfortunately it's not available at that link as of this writing. There are a couple substitutes that may work, and I've included the f3d and step files if you want to modify to your purposes.

Model is released as public domain, so do as you like. If you do make a modified version that you'd like to share, let me know and I can likely put it up here.