By multiple accounts, the Springfield service yard gate wouldn't be the most ideal due to the backstage stank-combo of FFB and Animal Actors. It could still very well happen, but I think a more straightforward location would be at the Sprung tent portals between MIB and Coke. Considering the Sprung tent which uses that portal has its new queue which is up along the side instead of being in front of it, that leaves a wide-open backlot dr which goes straight down to B108.
Yes, you would have two portals back in that location. But it's been done before and this year is a one-off with this type of situation.