It's not a stupid question at all, kudos to you for asking and doing your research before you get the puppy. I have 2 boxers [rescues] they are fine being left in the house together. The boy can be left on his own, no problems, the girl came out of an environment where she was kept with other breeding dogs, we cannot leave her on her own, we tried, but she sits by the door and cries and cries.
I walk 2 other boxers in different places, they are both in households with other dogs and they are all fine being left - I have never sign any signs of either of them being distressed/destructive around their houses when I have gone to pick them up, one set of owners are sometimes out of the house 7-8 hours a day. This said, these are adult dogs....
You have the advantage of hindsight with the experiances you had with your last dog, so while I cannot answer your question as I have never had a young puppy to deal with, I do think that the fact that the pup will have another dog for company will help alot. This combined with crate training and exercise will all help to negate the worst of S.A.
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