Q:

Strike could think of little he wanted to do less

Strike could think of little he wanted to do less. (Original is on P.S. below)

I can guess the meaning in the context, but it’s not clear to me what structure it has. This is the way I think: 

Strike could think [of little [(that) he wanted to do less]].

The embedded bracket is a modifier for previous noun ‘little.’ And the outer bracket is the complement for the verb, I think. Is this right, or do I have to think otherwise?
P.S. 
Was it because Anstis had spent most of the previous day Skyping Helen within earshot of Strike, looking at the newborn son he might otherwise never have met? Was that why Strike’s hand had reached without hesitation for the older man, the Territorial Army policeman, and not Red Cap Topley, engaged but childless? Strike did not know. He was not sentimental about children and he disliked the wife he had saved from widowhood. He knew himself to be merely one among millions of soldiers, dead and living, whose split-second actions, prompted by instinct as much as training, had forever altered other men’s fates.
      ‘Do you want to read Tim his bedtime story, Cormy? We’ve got a new book, haven’t we, Timmy?’
          Strike could think of little he wanted to do less, especially if it involved the hyperactive boy sitting on his lap and perhaps kicking his right knee. 
          Anstis led the way into the open-plan kitchen and dining area. The walls were cream, the floorboards bare, a long wooden table stood near French windows at the end of the room, surrounded by chairs upholstered in black. Strike had the vague idea that they had been a different colour when he had last been here, with Charlotte. Helly bustled in behind them and thrust a highly coloured picture book into Strike’s hands. He had no choice but to sit down on a dining-room chair, with his godson placed firmly beside him, and to read the story of Kyla the Kangaroo Who Loved to Bounce which was (as he would not usually have noticed) published by Roper Chard. Timothy did not appear remotely interested in Kyla’s antics and played with his lightsaber throughout. 
(The Silkworm, by Robert Galbraith)

A:

Strike could think of little he wanted to do less. 

Little means "few things".
Things he wanted to do less means "things he feels like doing even less than this thing".
You can think of that as "things he did liked less".
So there were not many things that Strike liked less.
So sure, some things would have been more unpleasant for strike, but not many.
This construction is quite commonly used when someone wants to express they like or dislike something very much, although it is not the best or worst thing possible:

I have seen harder puzzles, but not many.

Or, in the words of Johnny Cash (from A boy named Sue):

I tell you, I've fought tougher men,
  But I really can't remember when

So here Strike may be able to think of some things that he dislikes more than reading a story to Tim, but there are not many things like that. If you would make a list of things Strike does not feel like doing, reading to Tim would not be at the top, but it would be near the top.

