So basically what your going to need to do is learn to sidescr_ape learn to angle your armour learn to bait shots learn weakspots and what you can take on aka don't go to brawl with super heavys and similar armoured tanks and your golden also don't be shy about spamming gold you carry enough ammo. vs real armour you can't contest your going to be in more of a support role if you can't get a plate you can pen then track them if someone's with you who can or change the engagement fall back regroup flank etc make them give up cover to chase you
According to wotstars banana buster has the highest winrate while the boulder has 16th because it's less versatile, for damage banana buster is 7th while boulder is 20th keep in mind it's only a couple hundred damage between the highest and lowest ranked 1285 vs 902
Wot stars also says the banana buster is very strong and boulder is slightly strong.
I'm on record as being unwilling to take wotstars as a be all and end all but I know both of these tanks very well and think wotstars has it right. I was previously ranked 1st in both of them currently 6th in both due to not playing them properly for over a year I have a 67% winrate on them because I understand the hardware and what their good at.
Having good Knowledge of game mechanics you will be able to do reasonably well in them just turning your hull 30/40° even if caught in the open will make your hull a bad shot for most tanks granted the turret is weak vs equal+ tier Prammo and the drive wheel can be pened for damage and tracking frontally if unangled that's where other the skills come in. Simply rocking back and forth between shots makes you a harder target the gun hits hard and being pref your almost always top tier where it will happily seal club 5s and 6s and be a unfair fight for most 7s it's only some 8s it struggles with and t8 pen does outclass your armour especially if not used effectively