Here's the concept... take a Gorkanaught, beef it up as much as possible and do whatever you please. Add a KFF and lots of meks to get all your hull points and weapons back each turn. Heck, this might draw enough attention to let a wack of trukk boyz get across the board untouched.
(note: meks wouldn't be equiped with Kustom Mega-blastas)
Big Mek, KFF, 3 grot oilers, Da Fixer Upperz (115 pts)
Burna boyz, 2 burnas, 3 meks, 3 grot oilers (95 pts)
Gorkanaught, extra armour, grot riggers (275 pts)
Total 485 pts
You could do a similar combo with a Morkanaught, but since it can have a KFF you could just go with a normal HQ mek. Also, you can only have one Da Fixer Upperz per detachment. An alternative would be to have the Mek trail behind so he could give a KFF save to something else as well, but stay out of line of sight.
What does this combo do? Well first off you have a 5+ cover save from all attacks. Anything that gets through that has to penetrate 13 armour, any crew shaken becomes stunned with the extra armour. Next you have 5 hull points. Provided those don't all go in one turn you get to use your mek tools in your shooting phase to repair hull points, weapon destroyed and immobilized results on a 5+. In this combo you have three meks repairing on 5+ and the big mek repairing on 3+. Then at the end of your turn the grot riggers repair a further hull point on a 5+. On average you're repairing 2 hull points per turn and ignoring 1/3 of all incoming shots (invulnerable save against shooting attacks, not cover save). Of course its going to draw a ton of fire, but that's kind of the point. This will attract all of the deadly stuff leaving the rest of your army to get in the enemy's face and smash some skulls. You could double up on this combo, or do a similar one with a Morkanaught but then you're running out of heavy support options for other fun stuff.