I've owned my 1986 coupe for almost 5 years now. I think I got pretty lucky overall as the car was in very good condition with 42K miles. Now we're up to 50K. When I first got it I brought it to a local shop that specializes in Jaguars. The owner was impressed with the car, and went through and fixed a bunch of small items. I had the gas smell in the boot since I bought it. Not bad, but it is there. So the first year I went about changing all the rubber fuel lines in the engine compartment. They were original to the car. The next off season I did the same with all the rubber lines in the boot. I have not changed out the ones over the rear axle yet, but that will be upcoming as soon as I use up some of the gas in the tank. Over last summer the smell seemed to increase somewhat in the boot again. yesterday I got into it and found 2 places that were seeping ever so slightly. both were joints with the compression sleeves. I tightened them, but I wonder if that is enough? I also looked at one of the 3 lines that goes to the evap canister in the right buttress. It's the one closest to the center of the tank. There was a small amount of fuel in that line, and I was kind of surprised because the car has been sitting for a few months now and the tank isn't that full.

The car is registered as a classic and isn't subject to any emission standards, and I have to wonder if I wouldn't be better off to just have a fuel system that has a fill opening, a line to the engine and the return line, and simply get rid of the BS evap system and the charcoal canister all together, just to simplify the system.

Looking through the service records the recall on the tanks for pressurization was done at one point, and also the records are full of the previous owner chasing down a persistent fuel smell in the boot. I get that this is a common problem, but enough already. I've had hundreds of cars and motorcycles and even a few airplanes, and NONE of them ever had a fuel smell that couldn't be 100% rectified. In spite of the recall being performed i still had the occasional "whoosh" when stopping for gas and I did drill a small hole in the cap and vent it down the drain tube where the gas door well.

Also the carpet seems to be unaffected to this point, but there has to be a way to make a solid simple fuel system for this car.

 

I did as you suggest & just got rid of everything in the upper right corner (rochester valve, the 4 outlet little mini vapour tank). Tee'd all the vent tubes together & vented into a single line with an in-line furl filter then directly underneath the car.
I also found some small leaks at the compression fittings on the tank so used Loctite pipe sealant on them. I stuck rolls of paper towel around them & after a month or so they had clear marks from the fuel seeping.
I'm still not sure I've completely cured the smell but it is definitely better.

Oh FYI I recently changed the fuel hoses above the rear axle, & IMO there was really nothing wrong with the original ones. They hadn't really gone hard or cracked or similar.

 

rubber hoses over the cage were the cause of my gas smell in the trunk issue. They had small cracks that leaked under pressure but still seeped when not in use. The amount of gas leaking obvious since they were leaking behind the tire. The leakage would evaporate so I never noticed a pool but the fumes would go in the trunk thru the air opening and stay there.

I have to agree that getting rid of all that hosing and plumbing does sound like the way to go.

 

On mine, the thing that cured it was replacing the gas cap. Apparently because the fuel vapors are heavier than air, it would permeate through the sheet metal pocket and into the car. Of course I replaced everything that you have plus some before I figured it out. Cheap and easy.
I bought the replacement from Rockauto, and it looks like any old American car, but it fits. I think it also fits some older Ford vans.