I'm not sure if this will work for your son EandCmom, but this is a game my son enjoys to help him learn sight words, and I think could maybe help with spelling too. We make a memory game with index cards, one card with a word, and on the other a picture cut from a magazine that matches(you could even just draw a picture). (ex the word girl written on one card, and a picture of a girl on the other card)
When he's playing and flips over a word card, you can have him not only read it, but then have him spell it out loud, each time. so it would help him memorize the spellings of words.
Each week or two depending on how often he's been playing the game, we make a new set of cards (or whenever i feel he's mastered the words)
Anyway..that's my idea....hope it helps..
-Jenafur