First of all, Frank, the context of II Peter 3:14 is not about being declared righteous. Rather it is about holy conversation and godliness, and diligence in achieving the spotless condition described. That’s practical holiness, not a legal declaration, that is in focus.
As with the Bible, you take Ellen White out of context. The statement you quote from Steps to Christ, p. 62 continues, and says this:
"More than this, Christ changes the heart. He abides in your heart by faith. You are to maintain this connection with Christ by faith and the continual surrender of your will to Him; and so long as you do this, He will work in you to will and to do according to His good pleasure. So you may say, “The life which I now live in the flesh I live by the faith of the Son of God, who loved me, and gave Himself for me.” Galatians 2:20. So Jesus said to His disciples, “It is not ye that speak, but the Spirit of your Father which speaketh in you.” Matthew 10:20. Then with Christ working in you, you may manifest the same spirit and do the same good works—works of righteousness, obedience.
“So we have nothing in ourselves of which to boast. We have no ground for self-exaltation. Our only ground of hope is in the righteousness of Christ Imputed to us, and in that wrought by His Spirit working in and through us” (SC 62-63).
Notice how Ellen White is clear that the ground of our hope, the answer to legalistic boasting, is not to be saved by justification alone, but rather, to be saved by BOTH justification AND sanctification. Both of these she clearly states to be the ground of our hope.
The other passage you quote from Ellen White is clear that declarative righteousness "is accepted in place of man's failure" (1SM 367), not in place of his sanctified success. Ellen White is s clear as the Bible, as the above statement from Steps to Christ makes clear, that "both our title to heaven and our fitness for it are found in the righteousness of Christ" (DA 300).
Not a particle of support in either Scripture or the writings of Ellen White can be found for the popular claim that the only perfect righteousness believers can have on this earth is a forensic declaration. That applies to past sins only, according to Ellen White:
“Christ bears the penalty of man’s past transgressions; and by imparting to man His righteousness, makes it possible for man to keep God’s holy law” (6BC 1092).