How to pimp my IS-7.

Ey guys. First of all, I'm playing just for fun of it. Im not spending hours studying WOT mechanics, but after few years I've made it to my first X tier. Gotta say, I fell in love with IS-7. It's not the best, but gives me joy to operate. I'd like to invest my perks and additions wisely. By now, I have:

1. Commander. 6th sense, BiA, repair, JoAT, Mentor.
2. Gunner. BiA, repair, Snap shot, +1 perk to choose
3. Driver. BiA, Clutch braking, Smooth ride, Off-Road, repair
4. Loader. BiA, repair, safe stowage, +1 perk to choose
5. Loader(radiooperator). BiA, sit. awareness, repair, +1 perk to choose.

Equipment: Improved ventilation, stabilizer and gun rammer.

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By now I found that it's hard to kill, it's suprpisingly fast and manuverable, but my tracks are made out of plastic. I've started to think maybe it's a good idea to install modded configuration(+35% to repair time) since I've won one for some mission. Exchange it for improved ventilation, or the latter is far better overall? Is it worth it to take the Camouflage perk now? I know it's a HT, but every other perk now seems meeeh at best.