I have not seen suitcase weights on the front of an N. Doesn't mean it hasn't been done before. I have seen homemade weight boxes off the bumper. Hanging too much weight off the front bumper/ axle might cause access wear to your front axle pin/bushing. You may be better off with front wheel weights, if you can find them, or simply load the front tires.
They did make a brumper with weights for the later hundred series which added about 400 lbs but good luck finding them and when you do they won't come cheap. I have been after a set of these for my elenco for years. I call a guy who has them every 6 to 8 month just to let him know I am still interest and the answer is still no. He sez when he's ready I'll be the first. We all know how that sometime goes so we will see.
Kirk