I strongly recommend working from a hardcopy of SL. Somehow the ability to see more than a “screen’s worth” at a time makes a difference. Personally, I like a bound and printed (double-sided) version along with the electronic text and answers (the electronic version of the text might be single- or double-sided depending on the size of your monitor). Then you can read from the printed version, but use the electronic one to follow links, jump to answers, and so forth.
The full text is too fat to be usefully bound. Even if a printed version is not available (say as a reader from a campus bookstore), most any copy place will print and bind for you, often directly from the link. For Sentential Logic, and the two separate volumes of Symbolic Logic, you can use either “perfect” (with a tape spine) or “spiral” binding.
Of course, this costs something. But it remains a “good deal” compared to other options! T.R.