I’m of the mindset that Huerter should be the starter with the current roster we have now.
But if Brown disagrees and wants some sort of defensive presence starting at SG, my choice would be Keon Ellis. He’s been very good defensively, gets his hands on a ton of balls, and has much better size & length than someone like Mitchell. And unlike Duarte and Mitchell, he’s actually been knocking down the 3 ball at a high rate and volume.
Here are some of the SGs in the Western conference
K Thompson (GSW): 6'6", 220 lbs
T Mann (LAC): 6'5", 215 lbs
J Harden (LAC): 6'5", 220 lbs
A Reaves (LAL): 6'5", 197 lbs
D Booker (PHX): 6'6", 206 lbs
B Beal (PHX): 6'4", 207 lbs
K Pope (Nuggets): 6'5", 204 lbs
A Edwards (Wolves): 6'4", 225 lbs
SG Alexander (OKC): 6'6", 195 lbs
A Simons (Blazers): 6'3", 193 lbs
S Sharpe (Blazers): 6'5", 205 lbs
THT (Jazz): 6'4", 234 lbs
L Doncic (Dallas): 6'7", 230 lbs (officially listed as PG, but will play mostly SG when Irving plays)
J Green (Rockets): 6'4", 186 lbs
D Bane (Grizz): 6'5", 215 lbs
CJ McCollum (Pels): 6'3", 190 lbs
T Murphy III (Pels): 6'8", 206 lbs
D Vassell (Spurs): 6'5", 200 lbs
By contrast, these are our guards
Fox: 6'3", 185 lbs
Ellis: 6'3", 175 lbs
Huerter: 6'7", 198 lbs
Duarte: 6'5", 190 lbs
Davion: 6'0", 202 lbs
Monk: 6'3", 200 lbs
Colby: 6'6", 207 lbs
Kessler: 6'7", 203 lbs
Clearly, Kevin (and to a slightly lesser extent, Duarte), are the only two folks who have the requisite size (both in terms of height and weight) to play the 2. Ellis might put on some more mass over the years, but will remain slightly undersized for his position. Colby eventually might find minutes there, if his play and shot improves. He clearly has the size, and by some reports, good instincts. Monk is also slightly undersized, but makes up with his skills and fearlessness.
I included Kessler here, more to get the folks' reaction to him possibly being tried there. Given that our best backup plays a lot of minutes there, and we are trying to get one of our major offensive weapons there going (or trading for something significant), not going to happen. However, purely in terms of size, he's very similar to Kevin/ So, added him here.
Two of the best defenders in the above group (Davion and Ellis) are limited by their physical traits. Love Davion, but he's too short to play the 2, while Ellis is too light (and perhaps a tad short). Since our best players plays the 1, they will always struggle for minutes. Couple of years down the line, Colby might own that position. Till then, it should be either Kevin or Duarte.