Agreed. It's the same effort as center rail gaps. The relays we had under the layout for the first test of isolated blocks were from Azatrax, he has great products but don't think these were the right thing for this layout.
Ive seen you're previous threads with the one channel boards for about 2$
I have a 8 channel Arduino relay module. Just a little confused at where to hook the wires up to. (Coffee hasn't kicked in yet)