If by viable you mean wins more than it loses, I'd say yes, but that's up to the quality of your strategies versus your opponents.
If by viable you mean can beat tournament level lists played by good players, then it becomes very questionable.
Dark eldar sacrifice durability for speed, and without transports they lose their speed, so all you're stuck with is very fragile expensive units that cannot get where they need to be before they die.
And at this time, one of the few things that can keep your units alive, is highly ignored: cover
You're on the right track of course. You're army will probably consist of only things in the Heavy and Fast troop slots. The only unit in Elite can survive fire outside of a transport is probably harlequins. Well grotesques could too but they're not fleet and can't ignore cover.
Where you're going to have a problem is with troops. Doesn't matter if they have fleet, they're going to die before they get where they need to go. I'm pretty sure wracks would even die. A 20 man squad on something like a skyshield platform, or any fortification that gives an invulnerable save might work, and they could actually hold an objective if you can place it. And then sure you could take two squad of eldar bikes. But you only have three troop choices at that point. You could try taking hellions as well, but I've never thought of them as a good choice for anything really myself.
And that's where I'd probably give up the pursuit myself.
I go into every match expecting my boats to explode, it makes it easier to plan ahead that way.
Edit: Oh also, how are you going to deliver your WWP without a transport?