First the cap badge. It's my opinion. But perhaps if you have any contemporary illustrations of 95th Riflemen in the field with cap badges, you could post them. Even militia rifle companies rarely show a cap badge being worn in the field.
The point about the canteen markings was that they are virtually always depicted as being in white and on display.
My comment about the wooden canteen was not to say that it wasn't issued in large numbers, but that it wasn't the only type issued.
"Were all regiments supplied with the same type of canteen? Hamilton-Smith's works suggest not! With the Guards donning what looks like a 'visually' unmarked, black leather covered canteen, probably of pewter. A smaller, egg shaped, leather covered type of canteen shown on both a sergeant and private of the 87th. But even when a 'normal' canteen is depicted, Apart from the KGL Hussar mentioned above, no markings are shown."
Perhaps I should have made it clearer that I wasn't dismissing white being used to mark canteens but black must have been used too. Is there any evidence that these markings were displayed rather than faced towards the wearer?
As an aside, there is the picture by Loftie of an officer of the 16th in campaign (undress) dress (Suriname 1804), with a plain wooden canteen at his left side and a haversack at his right side marked up.
The Horse Life Guardsman and Artilleryman pictures you posted (I have the Vernet one). are very nice, but (the top picture especially) is post 1815 Vernet's is inconclusive.
As for artist's not depicting the boring parts of a cavalryman's dress. Are we to assume that all those artists got together and agreed collectively not to bother with equipment that bored the eye? Or is there more going on that we know nothing about?
Written regulations do not survive practicality in the field. Even the Duke said in so many words that he didn't care how they looked as long as they had 60 rounds and could fight. Indeed, If I followed regulations, I wouldn't have had two pairs of kidney pouches, an extra water-bottle pouch and a civilian type, dark olive green day-sac. Even later when PLCE was issued, I still used a civvi day-sac from time to time, and extra utility pouches
There is this picture 'Scots Greys in bivouac 1815'. by James Howe. that shows a mounted trooper with both haversack and water canteen being worn so perhaps I seemed too emphatic. I was silly to state that the canteen and haversack wasn't worn on the trooper whilst mounted, but I still say that perhaps it was discretionary whilst in the field. The other thing about the picture though, is the chap resting his head on his hand behind the sergeant in the bottom left foreground may be a rare 'depiction' of a trumpeter.
Going back to Infantry canteens. This well known, contemporary picture of a 3rd Regiment Guardsman is probably about the best example of how equipment was worn in fighting order.