I have a sliding door dog door but for the first days, maybe even weeks, it'll probably still take some learning as you go along to see how much anxiety she might have being left alone
and how destructive she gets. With Lady, we've had her for months and she still destroys the house when we leave. She gets into trash cans, recycling, eats shoes, gets into pantries and cupboards, climbs on the table, etc. I don't know how tall Sweet Pea is, but if Lady was any taller I'm sure she'd also be climbing on counters and things. We have childlocks on our cupboards but she gets in, so now I put a chair with a weighted box on it and block the pantry. I tuck the chairs in on the dining room table (she can't reach it without a low hair to use as a step), and I just have to close all the doors to all the rooms to the rest of the house, and put the garbage and recycling in one of the rooms and close the door, and we make sure she can reach nothing else in the house or she'll get anything she finds, take it through the doggy door, and completely shred it. When we first got her, though, she'd just shriek and whine when we left the house and get sick everywhere, even if it was just to the store really quick, and after about a week she began to start to not get sick but just get destructive. We've stepped out to get the mail and when we come back five minutes later she'll already be destroying everything now. Toys and treats and things don't help, she just gets set on destroying. I think because she used to be a stray she just is pushing her limits and is used to being able to go through garbage, and since she's afraid we'll leave her since she went throug many fosters then she has the bad separation anxiety.
So you'll probably just have to figure out how Sweet Pea will act when you start leaving her home and just keep trying to figure out how to accomadate her and stop anything she might do. She might be able to be distracted and e retrained by toys and kongs and things like that. We have a kong-like toy for lady called an Occupi. It has a main hole for a stick treat to put in it, and then it has a rim indentation on the outside to fill with peanut butter or other spreads, and then it also has little holes to put small treats in it, like cat food sized treats or sticks. It's made so there's different behaviors to target and entertain, and different ways to get each treat out. Lady is slowly starting to become more interested in hers, but Sweet Pea might be more toy and fold driven where it could be used to distract her right away, depending on how her separation anxiety might be.
Does she do anything right now when you leave her alone that might escalate when you leave her for longer hours?