Chris, similar to Dimi's approach, I ran insulated s/s pipes thru the tunnel & put screw-type a/c fittings on the ends to take the compression fittings on the end of the rubber hoses. (With the DRB, there is simply no room to run the pipes along the tanks).
At the back, I had 90deg fittings on the ends of the s/s pipes & just looped the rubber hoses around to clear the pulleys & get to the a/c compressor.
At the front, I brought the a/c rubber tubes up to bulkhead fittings in the bulkhead above the passenger's feet. I also brought the 2 heater hoses up to similar bulkhead fittings in the same area. (The heater hoses are attached to 45deg spigots on the front ends of the main cooling pipes & simply rely on the "suck & blow" effect of the coolant passing the 45deg spigots - works very well, & none of the problems of trying to get heater hoses back to the conventional take-off points on the water pump).
Inside the cabin, I have 2 a/c rubber hoses coming from the bulkhead fittings to the a/c evaporator, & the 2 rubber heater hoses coming from the bulkhead fittings to the heater coil spigots on the Sanden a/c evaporator / heater / fan unit behind the dash in front of the passenger.
My only criticism of the setup is the weakness of the fan in the Sanden evap unit - its ok in terms of keeping things cool (even on 35deg days), but it lacks the oomph to give you that nice blast of chilled air when you want it.
There seems to be no problem associated with running insulated pipes in the tunnel with the coolant pipes - the air coming out of the a/c is freezing cold - it just that there is not that much of it !
Kind Regards,
Peter D.