Hi Jim
The following scriptures are from the Bible (not the SDA's manual) and all seem to support soul sleep.
Acts 2:34 34 For David is not ascended into the heavens:
Job 14:14-15 14 If a man die, shall he live again? all the days of my appointed time will I wait, till my change come. 15 Thou shalt call, and I will answer thee: thou wilt have a desire to the work of thine hands.
Psalm 13:3 3 Consider and hear me, O LORD my God: lighten mine eyes, lest I sleep the sleep of death;
1 Corinthians 15:51-52 51 Behold, I shew you a mystery; We shall not all sleep, but we shall all be changed, 52 In a moment, in the twinkling of an eye, at the last trump: for the trumpet shall sound, and the dead shall be raised incorruptible, and we shall be changed.
John 3:13 13 And no man hath ascended up to heaven, but he that came down from heaven, even the Son of man which is in heaven.
How do you explain them?
And how do you explain that Christ himself said he would be "as Jonas was three days and three nights in the whale's belly; so shall the Son of man be three days and three nights in the heart of the earth. " Matthew 12:40
That does not sound like "paradise" in the heart of the earth.
Mark 8:31 31 "And he began to teach them, that the Son of man must suffer many things, and be rejected of the elders, and of the chief priests, and scribes, and be killed, and after three days rise again. " Christ said that "after three days" he would rise again - not during those three days.
Even the two witnesses have no life when they are dead for 3.5 days. Revelation 11:11 "And after three days and an half the Spirit of life from God entered into them, and they stood upon their feet; and great fear fell upon them which saw them. "
I see it as a difference between the body and soul/spirit:
2Cor5: 6 Therefore we are always confident, knowing that, whilst we are at home in the body, we are absent from the Lord: 7 (For we walk by faith, not by sight

Rev 6: 9 And when he had opened the fifth seal, I saw under the altar the souls of them that were slain for the word of God, and for the testimony which they held: 10 And they cried with a loud voice, saying, How long, O Lord, holy and true, dost thou not judge and avenge our blood on them that dwell on the earth? 11 And white robes were given unto every one of them; and it was said unto them, that they should rest yet for a little season, until their fellowservants also and their brethren, that should be killed as they were, should be fulfilled.
So the body is "sleeping" in the ground or urns or whereever while the soul/spirit is with God waiting for the resurrection!