A QOV made by you would be so meaningful. To keep it simple for yourself, I would suggest buying a patriotic panel and adding simple red, white, and blue blocks around the panel to enlarge it to the size you want. SITD or outline quilting would be fabulous. Pinterest has many ideas, like this one:
https://www.pinterest.com/pin/284289795198600830/
Most quilting stores sell QOV panels like this one:
https://www.fabric.com/buy/0473835/k...anel-americana
Good Luck! And thank your dad for his service.