You could give a go once, or every now and again. If you can do 5K on a treadmill then running 7 miles occasionally wouldn't cause much injury except for blisters probably. Ramping up weekly mileages too quickly is what gets you injured IMHO. If you were to run it, I'd allocate probably over an hour to be on the safe side, not including getting changed and showering.
+1 to the above.
When you feel that you can manage a 7 mile run, try a run to work; but do so at a
comfortable pace. I find that if I do a training run at an average of 8.30 - 9.00 minute a mile, I feel the after effects
much less than if I were to run at 6.30 - 7 minutes a mile. I wouldn't get too concerned regarding the pace at which you run; it is what is comfortable
for you that matters . . . . . . . and not picking up injuries.
I did a 19 mile run just a fortnight ago with 2,600ft of climb; I averaged just over 9 minutes for a mile - which on the face of it is 'slow', but it felt very comfortable and afterwards, I hardly felt as if I'd run.
When I 'push it', then I know that my legs feel it afterwards. Unless you are doing a specific speed session, I'd always run at a comfortable pace at which you could hold a conversation whilst running.