Right, but your doing exactly what I suggested. Almost every "I trained 12 hours a week" athlete did peak load hours more than 12 hours. And I can almost gurantee everyone did more than 2 hours in a training day, of which the OP has suggested he's bound do 1-2 hours max a day.
So all the info you were giving him isn't all that applicable in this instance. Cus if your saying they get in a 4 hour ride in peak hours due to time constraints that's still double the longest ride he'll be able to get.
So like I said an athlete saying this is his limitations and this is his goal....the 2 don't match at all. That's the reality of it, but again athletes are going to do whatever athletes want to do and if this is more just an suggested goal in the back of their head and this is the *only* event that will get them to live an active lifestyle, then by all means do it. Just take out that time goal, cus said athlete is not preparing properly to meet said time goal with the limitations he has. So essentially he imo is setting himself up for "failure" with respect to the "goal".
ETA: And I called out your statement for BS because I know that those athletes who "I did sub 10 on 12 hours" actually did weeks of more than 12 hours, thus invalidates the whole claim of "12 hours" to begin with.
-USAT L2 coach, M.S. Exercise Physiology