I have a 1999 CR-V EX, which is mechanically identical to your 2000. I've done a lot of highway driving on long trips (Indy to Key West, Nashville to OBX to Key West, Nashville to Bar Harbor Maine, and others).
My solution is to stop every 3-4 hours for fuel and to stretch my legs, and I turn the volume up on the radio.
And, if you add some sort of sound absorption padding to the hood you'll still hear the engine through the firewall. And it won't do anything for the wheel/tire noise.
If it were a problem for me I'd look at adding Dynamat or something similar to the interior to deaden all exterior noise.