Based on the rules in that league, it takes away one of the major draws of an archon(2+ invuln). That being the case:
I'd swap out the archon for a Liquifier Haemy(60 pts), then upgrade one of your wyches to a Hekatrix with a power weapon and phantasm grenade launcher(30 pts).
The Hekatrix will be your killy model instead of the archon, and will have AP3 in CC at the expense of the poisoned AP- weapon. The idea would be to start the Haemy off with the wyches, but when the wyches disembark, they take the pain token with them and the Haemy sticks with the raider.
So your raider will have a passenger able to fire off a liquifier gun, and your unit of wyches will have FNP, defensive grenades, and a Hekatrix w/ power weapon leading them. FYI, defensive grenades now blind your opponent on a failed initiative test, lowering their WS and BS to 1. Wouldn't hurt to toss one at a unit you intend to charge. If it succeeds, it'll likely double the amount of hits your wyches and Hekatrix score.
This loadout makes your list come in at 496 points, and I think the FNP on the wyches makes up for the loss of the CC only clone field.
As for your Haemy's surviveability, I'd just try to keep him hidden away in the raider, and hope they don't blow it up. Be captain jinkalot, and use your cover. The raider can jink, then the passenger can still fire at full ballistic skill with the current ruleset.
EDIT: If you just happen to roll an additional pain token for your combat drugs, I'd just keep the Haemy with the wyches and give up fleet. Can always accept challenges with your Hekatrix, and utilize "Look out, Sir!" to keep the Haemy safe from hits. The additional pain token for your wyches will be worth the additional risk.