Yes, I don't see why what you propose won't work. You may have to disable some stuff on the TPlink so you don't have 2 DHCP servers running. Note if you do any access externally into your network it's probably going to get messy.
Looking at that router, you sometimes have to be careful with what the describe as load balancing. This looks to failover when once connection goes dead, which I presume is what you want. Note the quality of this detection and speed of switching can be variable. It doesn't look to allow you to send some percentage traffic to each service.
https://www.tp-link.com/ca/support/faq/529/