Dave, I have been making a charcoal cannister for years for streetrods, never have I smelled gas in my garage and have done multiple cars, very simple also after your rollover valve, run the line from the valve up higher than the gas tank and make a loop (either out of hose or tubing) from there I pass it through a bulkhead to the outside of the car and I make a small 2" diameter x 7" long aluminum tube and put caps on each end then put a hose to the tube, I drill and thread the end cap and use an fittings, on the other end cap I drill a series of small holes so air can pass through the tube. Then go to Walmart in the fish section and get activated charcoal, fill a section of nylon panty hose tie it in a knot and insert it in the aluminum tube, your good to go with never a smell and the tank is well vented. I have made one for a VW with just PVC pipe and had equal success, you could do this and put it in the trunk and just put a hose on each end and run the hose on outside. Somebody is making one just like I mentioned (billet) and marketing it for a few hundered, but I made my first in 1998!
The whole thing looks like a large inline fuel filter just with charcoal in it