Someone (PO or factory) previously drilled a hole in my '48s bumper and put a chrome-capped bolt through it for the plate holder. Granted my '48 is pretty beat up and corroded now but a hole in the bumper can be made to look good. You might not want your plate that high in front of the grill.
My price list for 1948 cars and trucks shows a pair of license plate frames for $2.65. It doesn't say if that's for a truck or car or both. I had a '51 Chevy car but don't have pics of the front plate, just the rear.
34 Years. Now with a '61 261, 848 head, Rochester Monojet carb, SM420 4-speed, 4.10 rear, dual reservoir MC, Bendix up front, 235/85R16 tires, 12-volt w/alternator, electric wipers and a modern radio in the glove box.