[NovaBeJota]

kayak on the top of the cap, hitch mount bike rack, build a platform for sleep with storage under it (some camping and fishing gear) then place the remaining gear in the truck or next to your sleeping area.

Ditto to this idea. A lot of climbers do this to their vans and camper-topped pickups. Bear in mind that these guys and gals actually live in their truck beds, but you should get some inspiration if you go this route. I found a way-too-long description at Truck Camping - Outfitting and Living in the Back of a Pickup. If you want more pics, just Google "dirtbag climber trucks". A fair number of the image results will be vans, but there ought to be more truck ideas.

 

[NovaBeJota]

Another idea for future consideration might be a rooftop tent. That'd free up your bed for all the gear, and from what I hear they're very comfortable. The downside is that they cost a couple of grand.

On second thought, if you're planning on bringing the kayak along, its 13 feet are still going to be an issue...