Appropriate Field Modification or Farbing up a good coat?

[Redbeard]

Every time I put on my overcoat I find myself wishing I had some front pockets on it. I've seen reenactors put them on, usually a patch pocket, and I have found a bit of evidence of guys putting a less visible pocket in (the term eludes me, but it's slash in the coat that is re-enforced and lined). What I haven't seen is an original overcoat with patch pockets? Does anyone know of such an example or if it was common?

Would I be farbing up my coat to put a pair of patch pockets on it? I have the material left over from patching a pair of pants to create a pair of pockets. They won't match perfectly but they will be of the same material (just newer and less grubby and faded).

If it's not right, I won't do it.

[EWOAF]

Civilian overcoats often had them. Here's the younger photo of Fred Olmstead with his on. I've been wanting to copy that coat for some time and keep hesitating.