Can a certain boat and setup cause the other team to have a Fixer more often?

Absolutely, but that's the only data I have access to readily. Also the variation in matched games and fleet mates provides a fairly sizeable and representative pool for nightmare league to at least make a quick look at the win rate effect. This is all I have though, and I think more importantly how it affects different infamy levels would be important as well. IE, just because it's 55% at nightmare doesn't warrant a nerf if it's 40% at Ace/etc. I agree other factors are to be considered here, but I would definitely suggest and advantage.
I'm data driven, so I'd like to see some hard data on it from a source (I couldn't find one in a search either, hence the comment here). So, for now, the little data I have from a hundred games or so some months back is all I have. Again, I'll start filling it in, but if you want to provide some data, I'm all for adding that as well. Maybe the new patch also normalizes the buff also with access to all health perks, but it could also be the reverse. Maybe @The Grim Repair or others can help also on a thread or some data?

 

To be clear here, I'm only suggesting that the presence of a single healer in the game can be an effective increase in win rate, not that healers have a disproportionate win rate (ie being a healer will not directly and only increase your infamy). On some quick data with the new patch. Last 30 games that met this requirement (out of a total ~120 games, 30 of them had a single healer in the game), the healers team won 70% of the time (21 wins, 8 losses, and 1 draw). I'll keep adding to it as I go, and maybe others can chime in.

 

Double pulse kills it, as soon as you have good mobility and stick together with at least 2 of your team mates. Since I play fixer pretty agressively, I can back off, heal myself and then go back to trouble .

And no, I don´t really think that your gear determines your team. Yes the quality of the team, but not the composition.

 

That's because Fixer used to have less training trees and item diversity than everyone else, so it was faster to build a higher level boat, then being support to even higher level boats works as well. I'm not convinced the win rate is higher just because you have a Fixer on your team. It does help to have a Shooter/Defender fleet with a Fixer for many reasons.. coordinated strategy, and mutual protection.