The matter of the uniforms has been much exaggerated if one looks at the trial evidence.
One uniform was found in Paris which may have belonged to Raoul Gaillard, no-one suggested it was an imitation of any particular unit. Coster admitted to having a uniform made, 'to present himself honourably in the world'. A tailor had a bill for five 'uniforms' probably ordered by Roger (who denied it) but it was never quite clear what these were. Georges made the point that no uniform for him (XXL?) was made. No-one seems to have asked the tailor whether the discovered uniform was one of his. Roger may have ordered three officer's swords.
The four low-ranking chouans who remained at Aumale had had identical clothing made for them but both MMe Monnier who ordered them and the tailor who made them denied in court that they were military clothing. It was then disclosed that the men were wearing the garments in court and they were asked to stand up: the matter was not pursued further.
My impression is that something was being planned which probably involved Gaillard, Coster, Roger and Deville who were all officers rather than an improvised cavalry unit.