Chaos Servant Help... I'm Scarred to make any decisions

So, I've gotten to the rank required to open the short cut to lost izalith, just barely. (+2) However, I fear that in doing so, I have made a grave mistake.

See, I would like to join the Abyss covenant, mostly for the gear, but also for the ending(I know you don't have to be in the covenant for the ending). My problem is this: I've spent 30 humanity for the current covenant, but because I haven't placed the lord vessel, I can't get to the short cut to open it, and I wanted to open it for the head gear and saving solaire (He is my favorite NPC), However I fear if I were to join to dark wraiths, i would no longer be able to open the door. Now, can I use the evil primordial serpant to place it, and THEN join the dark wraiths? Like is there a way I could place it with him, and then go open the short cut, then join him? Or can I still open the short cut after I've left the covenant? I really need help with this, My game is put on a stand still until I can figure it out.

I'm playing the PC Prepare to die edition, this is also not my first play through. I beat it once on the 360.

Let me see if I got this right.

1. You can't open the short cut until the lord vessel is placed.
2. When you leave then rejoin a covenant, you're contributions get halved. Leaving the chaos covenant before opening the shortcut would mean having to reinvest 15 humanity (someone confirm?)
3. You can't place vessel at frampt because you want to be a darkwraith.

If I were you I'd stay chaos servant, kill four kings, and place the vessel with kathe. Don't join DW covenant right away. Instead, open the shortcut and do w/e you need to do in lost izilith. After you're done with lost izilith warp back to the abyss and join darkwraiths.

Hope this helps and welcome to the forums.

Thanks and thanks, truth be told I'v been really wanting a place to really discuss dark souls.