I Colorado CPW officer I chatted with said orange on a pack is a "judgement call" issue. The way the statute is written is somewhat vague when interpreted by a pack covering up so much of the inches. I've been using a blaze Grab-It lately, and a orange Sherman (YAY!) this year. In years past I just ziptied a $1 Hobby Lobby blaze bandanna on the outside of other packs and actually got kudos from officers that have checked me for that practice. Kind of like having crumpled beer cans in your truck, not illegal in their own right but is an easy lead-in for more probing questions to follow. I remember CPW having a video on their website a few years back that did state to add orange to your backpack - could not locate that quickly but this is a quote from CPW Website: (
https://cpw.state.co.us/learn/Pages/EHU-CH1-L12.aspx)
"Blaze Orange
Colorado law requires that you wear at least 500 square inches of solid daylight fluorescent orange, including a head covering, and it must be visible from all directions. Camo orange does not qualify. I suggest a fleece vest, a ball cap, and a stocking cap for the pack. Blaze hooded-garments work very well also. If your daypack is not blaze orange, don’t forget an extra orange vest to cover it."
If you keep an eye out at Wallyworld you can find short and long sleeve "quick-dry safety shirts" for a few dollars on sale in late summer. I usually buy a couple of these oversized and just put on over the top of my hoodie in mid-season hunts. Still have never found a good vest I like that is friendly to carry a pack with.
Lots of wiggle room for interpretation from statute to best practices, I will err on the side of best practices.