I thought the title of the OP is "what is there left to do?", not rehash another 50 pages about Campbell's wingspan and if it makes him likely or unlikely to be able to play LT.
Now I was NOT a big fan of the pick precisely because of the wingspan issue (not the arm length). Given what was available with the pick and the unknown offers we MIGHT have accepted to move down, the bottom-line Will Campbell was the guy we picked.
Here is what I DO know. Campbell was drafted to be a LT, not a G. I know that there were multiple guys who pored through every frame of 3 years of film on the guy and charted EVERY play, made note of who his opponent was, and determined the result.
Scouting is hard and you have to know what you are doing. 50 years ago I had a friend who worked part time for the Celtics as a scout. The very old amongst us would know his name, Rick Wietzman, who briefly played for the C's and won title under Bill Russell. Well anyway occasionally I would accompany him to games to scout players. Well to me, all the guys looked great to me. Fast, quick, skilled, etc Later, he would take the time to actually break down the players in detail and I began to start and see how they actually would fair at the next level and see their limitations. Scouting is a real skill and it takes time and experience to understand what to look for in players at the highest level of the game.
One thing that I found in my long coaching career I learned never to be surprised by how little I know and how much there was to learn. To be a good football coach, you HAVE to have a good-sized ego, but you also have a degree of humility and be able to admit there is ALWAYS something else to learn. In fact, that was part of the fun of it.
Campbell is here to be a LT and he will be given a season or two to prove it. So regardless of what you might thing about his wingspan the kid is going to be a LT for the near future. So granted he has a physical limitation to overcome, but he also has a lot of EXCEPTIONAL athletic ability to help him do that.
Rambling again. Let me get back on point. The "wingspan" part of this discussion is OVER and really shouldn't be mentioned again until the OL is in full pads and hitting some time in July. You know. The time when we can ACTUALLY see if the kid can block anyone.
NOW the time is to see who is still out there to fill in the roster so the best possible 90 players are there to start camp. There are still so excellent "names" out there at every position that will obviously improve the overall quality of the roster at every position. Want to improve the edge rush. Matt Judon, ZSmith, SBarrett, JClowney, and others are all out there. JSimmons is still out there if FS is an issue, So is DJ Humphries if you want to move Campbell to G right away.
You also have to balance your overall team building to who you bring in. Contending teams tend to bring in older players for a making a run THIS season or 2. Building teams tend to go more for younger players. Guys who are not playing to their athletic potential and hope a change of scenery and system will bring out the promise they have yet to fulfill. Guys like OLB KCaission fit that profile and there are others like him still out there.
THAT is what we should be discussing with OP like this, not regurgitating Will Campbell's arm length and rehashing personal issues with Eliot Wolf.