Parker does offer two row rocket launchers and their fabricator is local to them in Beaufort. You could call the factory and ask them to put you in touch with them. 252.728.5621
As Bobby mentioned, you could have one fabricated to your specifications locally, but you might find out that even with shipping, an east coast fabricator might be cheaper than one fabbed on the west coast.
Whatever you do, make certain that the mounting holes in that balsa cored top are properly sealed, preferably with an epoxy 'plug'.
Also, with the weight of a double row of rods, as well as the stresses of trolling, make certain that you add backing plates to your install.