Just in case I misunderstand, are you suggesting this is not achievable? As cosmicspacehead pointed out, we do love a good theorycrafting challenge here at GARD.
Please feel free to post your ultralight explorer build and I will gank-proof it for you at no more than a cost of 7% of its range (which I think anyone would agree is reasonable to be 'gank-proof'), I do not deny that extreme engineering is required, but it is to gank as well.

If you have the engineers you do not need to be a victim, and I say again...
The ABSOLUTE IRONY of this, is that we who pvp have to deal with 20 minute furballs due to the MASSIVE defense inflation that they provided to engineering EXACTLY SO THAT EXPLORERS DIDN'T NEED TO BE VICTIMS ANY MORE!! We ask why they don't use it and the answers just make me cry (it's too hard, I don't want to, I shouldn't have to, etc).
Explorers and traders seem to WANT to be victims, FD, there was no need for you to provide such amazing defense for so little overhead, so please can we lower this massive defense inflation? Thanks!
Disclaimer: Definition of gank proof: A ship that could be set upon by up to three medium ships with pvp griefer loadouts, and survive that provided the pilot did the correct steps in the correct order without panicking... Turn and boost toward (and past) your interdictor, put 4 pips to shield and 2 to engines, keep boosting. Now LOW wake (yes, I said low wake, it's perfectly effective because if you have a big enough ship after you to mass lock you you should be able to outrun it), and then as soon as you are in SC, turn around 180 degrees, pick a system that only an explorer build could reach (40+ly away) and jump. You are now safe.