Would 5 perk slots for Killer balance the game?

no, 5 is to much

No and until players and the devs all realize that using perks as bandaids to mitigate damage caused by problems that have gone unaddressed for years the game will continue to be poorly balanced. Perks are not the answer and have never been the answer on either Survivor or Killer

You wanna balance the game? Address the poor map design where they're either way oversized or completely claustrophobic. Their RNG system poorly generates tiles on some maps that lead to ridiculously unfair deadzones or ridiculously unfair chains of windows into god pallets all in a small area

Address how the main objective of the game (5 gens) has stayed the same for the past 6 years instead of making an early game collapse. Adding 10 seconds to gen time is extremely boring as Survivor and nothing special for Killers that play efficient squads in the majority of their matches

Address the fact that the devs continue to shun the idea of an early game mechanic because "We tried a test version of it privately and most of us weren't having fun so we scrapped it". Of course they weren't having fun, they actually had to do more than spawn right next to a gen and hold 1 button for a minute and probably got exposed by whoever was playing Killer. Also who cares if they have fun, what do the actual players want? The players are the reason the game exists are they not? They should be the priority above the Dev's personal interests

Address the fact that Killers in 2022 still aren't allowed to place map offerings that tremendously decreases the chance of going to 1 specific map instead of the opposite. Address the fact that us as Survivors can still cherry-pick cheesy maps of our choice to synergize with whatever build us and our SWF wants to abuse at the moment

Address the fact that it took 6 years of collecting useless data for them to finally start addressing the same issues that the best players/best content creators and thousands of average players have been giving feedback on. They tell people to give feedback instead of criticizing their company but then proceed to ignore the majority of feedback and only selecting the parts they agree with regardless of how it effects the game

Address the fact that MMR was falsely advertised and is the same exact system as the one they publicly admitted to scrapping because "It only tracked escapes and kills and we felt that it wasn't a good enough indicator". The balance conversation always gets altered because people cite skewed statistics as proof of things being fine when in reality the MMR system itself creates mismatched lobbies for both Survivors and Killers. You can be trapped in MMR hell with teammates way below your skill level and the Killer can also go against people way below/above their Skill level even after they play a decent amount of matches. No perks fix this issue

Address the fact that Survivors can que up and freely change their character/loadout but Killer was updated a while ago to be locked in to one character. Us as Survivors can bait and switch in any way we want up until the last second but the Killer can't have an option of 1-3 characters in the same MMR range that they want to interchange upon seeing Survivors making adjustments in the pre-game lobby. Either let both sides make limited adjustments or both sides make 0 adjustments

Address how the game is balanced more towards SoloQ than SWF yet SoloQ still feels miserable for the majority of players due to outdated mechanics. They never added a totem counter into the UI. They just now in 2022 made it so that you don't need to run BT by default to save yourself from getting downed immediately after getting off the hook. They just now made it so that you no longer have to run perks just to make kicking a generator actually do something useful

TLDR; They take years to collect data that aligns with common sense observations that even the most casual players have been pointing out since 2016. Perks are used as bandaids to fix problems that should be basekit and to disguise outdated issues that have still gone unaddressed