Why 4600 rear shocks? Makes no sense, those are stock length.
You MUST have written that backwards with OME rear shocks and 4600 front struts. You really want to have longer rear shocks.
You absolutely DO NOT need longer shocks in the rear for a Commander with a 2 inch lift.
If you want to install longer shocks in the rear, that's always an option - but it is not necessary.
People seem to have this misconception that having longer shocks (Bilstein 5100's for example) in the rear will raise your rear end and they absolutely will not do that by themselves, regardless of what setting you put them on.
They are just shocks, you will not raise your rear end the slightest bit by installing rear shocks that are longer than the OEM shocks - unless you specifically buy longer, load-leveling shocks, which are typically more expensive - or if you change the springs AND the shocks.
Bilstein 5100's - which are longer shocks, are not load-leveling shocks
The fact of the matter is, unless you plan on installing an even larger lift in the future, like a 4 inch super-lift, there is no performance advantage or benefit gained by putting 5100's, or any other longer shock in the rear, unless you do hard-core rock-crawling on a regular basis, where your suspension in the rear may benefit from having more travel from a longer shock.
In that case, I can understand doing it - but for normal, everyday off-roading, there are no benefits gained from a longer shock.
The Off-road 4x4 shop who installed my 2 inch Rough Country lift kit, (Southern Performance in Virginia Beach, VA) which is a very reputable shop that specializes working specifically on 4x4's, would not install Bilstein 5100's on my Commander and actually recommended the Bilstein 4600 HD shocks & struts with my 2 inch lift (which is actually a 3 inch lift with my larger tires) and that's what I went with. I'm very satisfied with their performance and haven't had any issues whatsoever off-road or otherwise.
I understand that Bilstein 5100's actually do fit Commanders - despite Bilstein's website stating that they do not, but again, unless you plan on installing a lift of more than 3 inches or doing hard-core rock-crawling on a regular basis - what's the point?
If I was going to question anything about what the original poster said, I would ask him why he doesn't just go with Bilstein HD 4600 Shocks & Struts?
The quality that Bilstein offers is an upgrade over the OEM shocks & struts, so why not upgrade the front & rear suspension as opposed to just the rear?
Stock length or not, the Bilstein 4600's are a nice upgrade - and I am speaking from first hand experience.
Here are some pics after I had mine installed;
Here is a pic of my ride next to a bone-stock Commander to give you a little more perspective: