I live in a resort and the speeds of the free WiFi are just OK, can I setup my GL-AR300M to connect to multiple AP’s and bridge them into the LAN port that is then plugged into my full size router?
If you want to connect wirelessly and bridge, then there is a problem. Wireless bridge generally means WDS. That needs the resort wifi to support WDS.
But I think you are not means the above. There is no meaning to bridge to the resort wifi.
When connecting to the resort wifi, it is better to use as WISP so that it create a firewall. If you still need to connect a full-size router, then it is better to bridge the full-size router to the mini router. This should be done in the full-size router.