Local doesn’t have an option built into it to specify a temp directory, it just uses the same mktmp mechanism as the rest of the Linux ecosystem.
I haven’t tried this, but you might be able to run Local in a shell where you configure the $TMPDIR variable.
I think the command would look something like:
mkdir -p ~/.config/Local/local-tmp-folder # create the folder on your user's partition
export TMPDIR="${HOME}/.config/Local/local-tmp-folder"; /opt/Local/local # or wherever Local is installed to
I’d be curious to know if that works for you!