Well, I finally got the T-28 HTC. As expected, LT-15 was the worst end mission out of all of them. I was able to do dmg/bounce the 10k for HT-15 in my IS-7 once, but the team lost so I didn't get it with honors. It took me about a week and a half of grinding to get both the HT-15 and LT-15 missions and I'm a fair player (1900-2000 Win8 and a 60-day 56% win rate).
The T28 HTC is surprisingly more fun than I thought it would be. As you may expect, it's fairly slow. But it's not T95 slow. And it actually has good frontal armor. So as long as you're up against an equivalent or lower tier opponent, you have a pretty good chance of bouncing a lot of shots. The thing is starting to grow on me. Maybe in part because it looks so darn weird!
So, I've started on the T-55a missions now. Set two vehicles (or the same vehicle twice) on fire in the same match? Really WG? I hate the RNG based missions like these. There's just too much of a luck element involved.