Definitely possible.
You could have a multistage missile with one stage consisting of a moderate-power engine and fuel for good range, one attack stage consisting of a high-powered short-ranged missile, and multiple decoy missiles of size one. To pinch pennies, these could have no agility, either no warhead or a 1-power one, and therefore a lower-power engine to achieve comparable speed.
I'm not sure if the AI will prioritise them in final fire beam defence if they are a tiny bit faster, and would therefore impact first in the same 5-second interval.
However, you could avoid overcomplicating things and just use small ASMs instead. Either for a uniform second stage payload or directly, depending on your range requirements.
Keep in mind that small missiles need to give up more performance for long range.