While Maxwell did occasionally design drivable or (sub 300 yard) par fours, it isn't exactly something he implemented at every site.
Two of the most famous examples are on collaborations with Alister Mackenzie: #17 at Crystal Downs, and #6 at University of Michigan.
The shortest example is #10 at Twin Hills, at only around 250 from the tee on the direct line. Though today there are more trees short right of the green.
Second, #5 at Indian Hills played right at 300, but slightly uphill and with two bunkers guarding the front. In the image below it plays from the tee in the top left to the green in the lower right.
#12 at Mohawk Park plays at around 290 from the common tee, though though 20 ft rises in elevation.
#14 at Dornick Hills also plays well under 300 but has also has a rise in elevation, and those attempting to drive the green may have difficulty with trees or bunkers.
Where else did he build par fours that were no longer than 300-310 yards?