Advice on gear for DJing football games

I would of course rig the mixtrack with an external mixer. You can get a 80-100 bucks “mini-pa” mixer from behringer or peavey that will get the job done nicely, used prolly for 50-60 bucks.
For the mixtrack you need an external soundcard, there is a really cheap one from Numark that gets the job done, or even the gemini is reasonably OK.
Then hook up the USB soundcard on one of the stereo channels of the mixer and the other 2 channels on the other inputs and you’re done.