I wanted to take clen at the same time at 40mcg daily for the first two weeks and up it to 80mcg daily for another 4 weeks
that's not a good plan of running Clenbuterol.
first, you've got to start at 20 mcg/day
second, you shouldn't stay on the same dosage for longer than 2 weeks
third, 80 mcg/day is a high Clenbuterol dosage. Better titrate it up slowly just to see how your body reacts.
you can go for: 20 mcg/day for 2 weeks and increase by 20 mcg/day every 2 weeks until side effects become too much (but never more than 100-120 mcg/day) and slowly reduce down.
Any advice as to whether this is a good idea?
you can run Clenbuterol during PCT as it doesn't touch your hormones. But it would be better to run it during cycle as it works in synergy with steroids (anavar, testosterone and/or others). Additionally, PCT is mostly to recover back natural testosterone production (and hormonal balance) but it is a period where your body should detoxify from all compounds.
So, while you can, I wouldn't. Better add it during the cycle