Back when I got my Europa, it was said that steel belted tires would not work on Europas (I don't know if it was true then - they were a fairly new construction then) and Dunlops were supposed to be the best. The rears would last much less than 20,000 miles (I don't remember exactly but it might have been even less than 15,000 miles). The fronts would last 60,000 miles (unheard of life for the day). I think the Dunlops were much softer than most tires. Back then, I also heard that many Europas came with very excessive toe-in - like 1 degree or more- (I might have heard that from someone at the Lotus distributor I used to hang out at, but it was a long time ago so I'm not sure). That didn't surprise me given the short life of the rear tires and that it would be much better to err on the side of safety.
Unfortunately, I haven't driven my car long enough to comment on the tire life. It wouldn't surprise me to find that the rears would wear much faster than the fronts given the weight and and power that goes through them, and of course your are correct that alignment will play a big part.