New to the forum and new to Subaru

My buying a 3-year old hybrid XV e-boxer recently followed the demise of a 30 year old Landrover Defender. Apart from anticipating a long time learning what all the little signs mean, it seems a very nice motor. However, I can also anticipate trouble from the lack of proper spare wheel. Nowadays there is a real risk of punctures, especially in rural areas, and I live in one in Scotland which could be described as "a bit out-by", and have suffered quite a few punctures which include tears of the inner and invisible part of the tyre on our other car, a Skoda Superb which is getting a bit elderly but has otherwise given good service so far. That too was initially offered without a spare wheel, but I insisted on getting one. With the Skoda, however, there was plenty of room to carry it; it seems that the Subaru lacks that room. My first thought has been to have a "box" on top to carry at least a proper spare and a good jack. Would there be any problem in doing that? The first question then would be where can one get a proper wheel to carry as spare, (not just one of those restricted to 50mph)?
I would almost suggest having two such spares, having at the end of last year (with the Skoda) had a double puncture in a wild part of Northumberland, in a place where several other cars were also affected before and after us. In theory the box solution could solve that too. In the event, the AA came and helped brilliantly.
Why is it that nowadays motor manufacturers in general are so reluctant to join the real world and accept that a proper spare wheel is still not only desirable but necessary? Without that one has to hope, generally in vain, that the local governments will see to proper repairs to their roads so that potholes etc are not so prevalent.