All of my shimano levers are inside shifters; right next to the shifter feels about right for me, though there is scope for moving them even further in.
I am pretty sure you cannot achieve the 3.5-4cm you desire with these new levers, when you said 'bit too close', I assumed you meant couple of millimeters or so; even 2cm from the bars when fully pressed is rather far. Personally, I would be looking for not more than 1cm, because the closer the lever to the bars, the less effort it takes to apply the brakes, and keep them applied; it makes huge difference on prolonged descends, where even couple of mm difference is noticeable.