Yes, that is phoneme reversal. And wait until you see how he does on multisyllabic words...
Phoneme Reversal is the name of one of the supplementary subtests in the CTOPP. Unfortunately, it has no equivalent in the CTOPP-2, which is the latest edition, out this past year. If the district gave him the CTOPP originally, they should already have the materials necessary to administer Phoneme Reversal. Some other measure of sophisticated phoneme manipulation would likely work as well. It has to be something more than simple deletion or blending, like reversal or substitution, since he's already demonstrated age-appropriate ability to elide and blend. (Granted, 2SD below verbal ability.)
The TOWL will be good for exposing written expression difficulties, as distinct from mechanics. You can also consider using a Six Traits rubric to qualitatively assess his writing products vs classroom expectations:
http://educationnorthwest.org/sites/default/files/new-rubrics-3-12.pdfAbsolutely, you could give it to a bright, engaged, education-oriented babysitter. It is literally scripted ("Say, '...'"). The main thing you might have to discuss with her is how many successful reviews is your threshhold for moving a phoneme/sound/rule/word card to the mastered list, and maybe some means of tracking which words are accurate/inaccurate on any given session. I keep it in my head, because I'm the only one teaching, and I only have one student--and I'm not too concerned about reviewing an extra time or two. You might consider photocopying the list of words taught from the back of the teacher's manual and using it as a checklist for words mastered/words to review/number of times in a row correct, or whatever metric you want to use to decide on mastery.
I take an errorless teaching approach to the reviews, immediately correcting every error, without giving my child any overall score. There is an understanding that mastered words will leave the rotation after a few sessions of correct, fluent spellings, and that more challenging words will remain until mastery. I plan to accomplish a certain amount at each session, but prioritize a short, successful, happy session over pace, as we were starting from a negative set toward writing and spelling. Because I can adjust how much practice with letter/phoneme tiles we engage in before writing any words down, by the time we reach written work, the success rate is usually high, which is satisfying for both of us.
