For what it’s worth, it’s possible. I joined a few temples where the access room was planted midway in second chain. I haven’t seen one temple with the first chain (which connects to atziri) connect to the access chamber as well, maybe it’ll create some sort of bug where you can’t access atziri no matter what.
Whether you want to set it up? It’s incredibly tough because you need a free sac chamber to cut it off after you join it via Roman road. You probably already need one to use early on when building your main chain after the spymaster barracks, and you only ever get 2 uses from a sac chamber (and the rest of your temple life). Which means you don’t have another sac to use for when you’re finishing up the first chain with thamaturge and corruption chambers. The end chain can still be finished, however much more tedious. All in all expect maybe 50-80 more hours just to set it up on top of the 2-300 hours expected for the full temple.