Given how far into this build the Jazz are, how relatively wide-open the path to the finals are (I believe they are, again, relative to most years), and that Mike and Bogey aren't going to be better than they are this year, I think going for it this year is still maybe the best opportunity to do so. Maybe Barnes becomes the super sub if you get him? He does not round out the main unit, he does the opposite, actually.
Barnes or not, if you can rebuild the bench to be a stable of hustling defensive players then that is probably the middle-ground in terms of how to change the roster before the deadline and keeping an eye to the future. Namely, Smart and Kenny who could be serious contributors and fallback main-lineup players (in case of injury, trade, or special lineup). I think you could get both without sending a 1st, Conley, or Bogey. So that's where I'm landing for my wishes this deadline; Smart and Kenny (for Ingles, Clarkson, and non-1st sweeteners if necessary).