It would be a very tough decision, but out of my collection I think I would end up with:
Shotgun - Mossberg 500, 20" removable choke barrel (and a 26" field barrel if multiple barrels are allowed under the "rules")
Handgun - GP-100, 4" barrel
Rifle - This is the toughest one, but I think that I would have to say my Marlin 336 in .30-30. But, a very very close second would be my Marlin 795 .22. Both are light and slim with quality iron sights (williams and tech-sight respectively, no optics to fog, break, hang up on stuff etc.), very packable. The 336 has the hand up in power, the 795 has the hand up in ammo packability.