I have been reading through some of the 13th Age rules on combat and I was particularly interested in the way that system handles combat range. While I am loving D&D 5e, tracking distance and positioning can be quite a pain sometimes, and often times when I am trying to describe the scene players will ask me to draw out the locations of the enemies. If I can simplify the way range and adjacency are determined, I suspect it will help to make combat much smoother.
I don't want to adopt the entire combat system, just the way positioning is handled. I don't want to modify opportunity attack rules, the action economy, or anything else of the sort. I'd like to retain as many core 5e rules as possible, and adapt them to work with similar 13th Age mechanics (such as the 'Intercept' action, which I imagine would translate to Opportunity Attacks in 5e).
My question is, how can I integrate the 13th Age range system into 5e? What problems might arise from this, and how can I solve them? How might area of effect spells, ranges, and move speeds be accounted for when abstracting distances to broad categories rather than 5' increments?