I agree with Dave...not all bodkins are the same. They all tend to be larger in diameter than the ferrule before they taper to a point. The ones Matt showed, available at 3Rivers, are not very wide, but they are wider than the ferrule and arrow shaft. I tried some Ace Classic points which are similar to bodkins but are even wider, and they were terrible on targets. When I pulled arrows from a foam block they would tear out chunks of foam like a broadhead, as opposed to the smooth removal of a field point that is the same diameter as your arrow shaft (except for the narrower taper up front). The dense foam of 3D targets also closed up behind the wide part of my Ace points, making them much harder to pull out than field points. I suspect that would be true of all bodkin styles, just in varying degrees depending on the diameter.
Also, I've participated in medieval reenactment for over 20 years and I have been to a number of shoots were bodkin points were specifically prohibited. For me, it is not worth the hassle. I have period arrows with examples of period points and broadheads for historical demos, but for archery practice and events I use standard fieldpoints.