I've tried to make Bridge work in these lists, and have found that like you suggest, it pushes the build too far in to Dredge territory at the expense of the other gameplans.
Regarding Ichorids: out of the several dozen lists I've tried, those with Ichorids have fared best for me. The list I 5-0ed with didn't have the Ichorids (looks like the list above), but on the whole the versions with some number of Ichorids have done best. I kept finding that the Dredge plan Game 1 is a little too anemic with just the Bloodhasts/Amalgams, so I've been trying to give it just a little more strength.
I have also wanted to explore Ballista in these shells, but have hesitated to explore that in the current list because of the dis-synergy with Null Rod. I think there is potential, though, perhaps in a very different list or for matches where Null Rods don't excel.
Also, after a month break from leagues, I took out the below list last night and ran back-to-back 4-1's:
Only losses were to Uba Stax (how fitting in this thread) and Outcome, both in Game 3.
Life From the Loam was fantastic all night. It was responsible for several match wins and felt much better than Crucibles when I've tried them. As both a tutor and recursion engine for the Depths plan, I am optimistic about its role in the deck.
Cursed Totem is a nod to Shops primarily. Shops, for me, has been the worst match-up for these lists. Null Rod is the best card in this match up, and buys a lot of time with Hollow One as a wall. Cursed Totem gets pretty close to Null Rod number 5 in that match-up.
Last night brings my last 7 leagues to 26-9 (somehow managing not to 5-0 in that span).