I hope that you read my previous comment - on previous page, I summarized all there.
Knowing your current status it shed a bit of light as to why we disagree on this topic.
From a starters point of view, which I am still, I have to sincerily disagree with your words about Boba, to an extent. Seems you didn't fully understand what I was getting at with my prolonged post.
Bottom line comparing Boba to QGJ - in begginer/intermediate level arena Boba is by far superior with his better and more versatile skillset. QGJ is just a dmg dealer, whereas Boba can be so much more, depending on the situation, especially taking into account his base speed.
Your guide is focused on getting best end result. What I'm suggesting and advocating for is to get similar end results, but better midway results. My point about Boba and QGJ was, that you SHOULD farm them both, but switch begginer priority.
Now here's my experience talking - by lvl 49 and onward I had QGJ max geared up (having 3-4 spare levels till next gear will be available, he is easy to gear like you mentioned). In addition, by lvl 56 QGJ would be max tier (switched farming to Boba after QGJ 6*).
The point I was making is - start off with Boba and get him to 6* or max out. You should be able to do it by the same time as with QGJ or faster if you use hard nods occasionally. You will get a fully functional and powerfull Boba by lvl 52-55 ( he also gets his tier7 gear much faster than QGJ, its next tier thats crippling for him). If you start QGJ farm after Boba, I'm preety sure you'll get him fully unlocked and geared up around 66-68lvl. By then Boba will get left behind and you can easily switch to QGJ if needed.
About Phasma - like I said, with Boba and Biggs roaming around on lower level arena squads, she is made redundant and too slow to make an impact. I can easily see her more viable with Boba in her team. Maybe it would change at higher levels - I yet need to wait and see.
To sum up and as a warning - one of my yeaterday's arena fights
prnt.sc/dqp7dlAnd that's not my top tier opponents, they were similar level, but faster Boba. You can imagine what's going on if opponent has chaze/wiggs/boba team... I still manage to get top10, but it's so painful and RNG dependant.
I commend you if you were able to get top3 consistently with your proposed squad. Seems RNG loved you or I'm just crappy as hell ;) Or maybe my whales are just a new genetically modified breed ;)