The frames are the same size, the dust shield is different between commander and government size frames.
The only real difference in concealing a commander is the shorter barrel makes it a little more comfortable IWB. It also doesn't hang down as far if you carry OWB.
I bobtailed mine and it made a big difference in how much it prints.
You're looking at at least $300-$400 in tools to fit the barrel, slide to frame, sear jig. That's just bare minimum basics and assuming you already have good stones and files.
IMO, unless you have a very good understanding of how to fit parts and more importantly how the parts work together, a few books, maybe a friend or a gunsmith to help... I would recommend buying a complete pistol and changing parts and doing upgrades to it. That's what I did, bought a Ruger CMD, did the bobtail, a few internal parts, sights and cleaned up the roll marks. The only thing left to do is a Harrison design true radius ignition set and have the front strap checkered.
Best of luck with whatever way you decide to go, building a 1911 is on my list of things to do.
On a side note, I find the commander sized pistols to be a little more balanced, not so nose heavy.