When it comes to rushdown matchups it can be pretty awkward for Duck Hunt. From my experience it's best to either take them to a very large stage to give you a lot of space to set up a wall at the beginning of a match, or a very small stage so your projectiles take up a larger percentage of the stage area. When they have you off stage, always keep the can above you while recovering to keep punishing your recovery as awkward as possible for them. Not too many Duck Hunt's take advantage of this but the can explosion hit-box comes out frame one, so it can be used at the last second to trade with an off stage punish to have the explosion hit both of you and knock you both back onto the stage (
https://gfycat.com/QuaintIncompatibleDeviltasmanian ) and back into neutral. Lastly, a good thing to do is to camp around your can with your shelf up when you know they want to rush in as a bait. This will cause them to attack your shield and hit the can, which will make it blow up without you hitting the button. If you hit this, it can combo into a back air which can put them into an off stage situation.
Sorry if this isn't worded very well, never post on here. Feel free to ask if you need any clarification on anything I said.