Yeah, if you only use companions then a Wizard is going to be a rougher start. Though if you fill in your party with temporary created adventurer's at the inn, then it's not so bad. Thankfully in Deadfire it's better if you go the companion-only route. It doesn't take too much time to acquire all the companions if you follow the main story and check out buildings and named NPCs.
First playthrough is Easy. Companions only in this party. A party that doesn't stop, you all, because it's Easy. No teamwipes, no real issues other than getting engagements set exactly the way I like. It's boring but it's fine, I want to read and I want to learn the mechanics as best as I can. There will be multiple playthroughs.
How far in are you and what's your party? Early on, heavy armour is disproportionately valuable, so don't feel bad about sticking even your back-row people in sturdy gear. Late-game armour has trouble scaling to match damage output, and you get more ways of boosting up your defences, so you typically strip down a little as you get higher level. If you're having trouble with the Temple of Eothas, don't bash your head against the wall: it's a very hard (and entirely optional) dungeon. Feel free to move on, grab a couple more characters, and come back with bigger party (and an anti-spirit sword).
I'm knocking around a lot. I'm on the cusp of the animancy hearings but I'm doing any and all side/character quests I can dig up. I'm stalling on animancy because I don't like what the narrative is doing, I'm getting pushed into a Decision on animancy. There's a lot of goddamn story, souls and gods and ruins and lots more souls.
I feel like I'm fairly far along (lvl 9), but I'm playing sloooooowly so I don't have a sense of main story playtime vs side quest goofin. I have intentionally avoided the internet for tips, etc., I'm reaching out to CAG as a trusted source.
Party is currently Farmboi tank, Balletina and Kane Train offtanking, Firepants Doorantz supporting frontliners with ridiculous buffs (so ridiculous), Underwhelming Inuit Deeps with Nonthreatening Off-Foxtank, and Confused Wizard (hi that's me) trying to figure out if she's (A) debuffing and spamming slicken or (B) waiting for a chance to flank the line and light em up.
I'm slowly understanding the deal in combat. My tactics are very conservative (self-evident). We form a tidy line, with wizard on the weak side for flanking once a makeshift line is established. Engagements take a while to resolve as I lack real power. The factors I understand that contribute to a lack of power: (1) my party composition (2) my unwillingness to go full-on angry mage with my main (3) I'm mostly unsure of how my enemy debuffs improve my squad's damage output.
Strategically I am building each character with as many relevant passives as possible. I take no "per rests" skills/talents. Frontliners are shielded up. It's a real no-nonsense party, we're not a flashy bunch.
Again, I'm playing on Easy. A "bad fight" is one that doesn't end with me feeling in full control -- I don't mind things going "wrong" provided I resolve it cleanly. My one almost-teamwipe was a vampyr on Od Nua Lvl 8, I finished his quest, then replied "Attack" when he got sassy without having my party composed before initiating chat. Turns out he's a charmer. Nearly charmed us to death.
Your tip on armor is noted. I had been avoiding plate for my paperdolls but you've provided the push I was needing to armor up. Although, am I too far along to benefit?
I'm looking forward to advancing to a tougher difficulties. One thing I really like about the AI is that mobs seem to have no difficulty identifying my damage dealers, as I noted earlier.
Oh, and I ditched Aloth. Who can only be Aloth, he doesn't get a pet name. The beagle I picked up along the way gets a name ("Ralph"), Aloth doesn't. I was very happy to take him down in the Sanitarium and push his character quest far enough along that I felt like, Okay, it's time to ditch this punk. Ditched him hard, went Underperforming Deeping Inuit, haven't looked back.