Yes, you can add braid using a uni knot as long as there is enough line to fill to the point where the knot is fully covered by line for a full cast (if it gets exposed during a cast, it can cause issues with casting
But don't let all the options and choices overwhelm you
But there are several more great baits with internal weight systems to help with casting on the market now, like the Ark MiniDiver and SPRO Little John Micro DD, which have different body styles but also attack this 5- to 10- foot range well in the winter
I've been wanting a 3-weight for years, since my 5 weight is far to big for most of the small spring creeks and mountain freestone streams I fish, but have been unwilling to invest the money in a quality rod
Therefore, I like the bright colorations that end up being around the primary colors
Rod G Loomis IMX Pro 883C BJR: Reel Shimano Metanium MGL 150 B (HG): Line Power Pro Maxcuatro 40 lb Braid: Leader Sunline Saltimate System Shock 20 lb: SOFT JERKBAIT COMBO