I like the idea of the Junkas
There are many klans, warbands, tribes, and other gatherings of Orks.
BlackSpike leads the Evil Moonz, a Bad Moon off-shoot klan that spends all their teef on fast vehicles and red paint
As BlackSpike's warforce is composed of the remnants of his Epic Waaagh (I used to play epic scale, with all 6 klans, back in the day, and am now re-building it with
40k!

), most klans are represented (apart from da smelly Goffs!)
The Big Six klans are just the most numerous across the Galaxy, but there are many others around. Some are off-shoots (like the Kult Of Speed, and the Evil Moonz), others are very similar to existing klans (Da Junkas sound a bit like Deff Skulls, lootin', nickin' an' re-buildin')
So, overall, nothing wrong with building your own klan! If you've got a theme, a story and a paint-scheme, go for it!
It's a big Galaxy out there! Plenty of room for some more klans!