Your client "forgot" he had $165k in assets? How much income did he "forget?" Did he deduct property taxes, registrations, heavy road use, maintenance, fuel, etc all those years? I believe the tractors depreciate over three years and the trailers over five, so most of the expense is behind him. Form 3115 is the only way to go.
Reminds me of a client I had once who forgot he was married! And I had a client this season who only had one W2, nothing else, and guess what he forgot to bring to his appointment? My memory ain't that great either, but......