JDUB hit the nail on the head perfectly. This is the perfect time to work on fundamentals of spinning and riding switch. Your son is having fun, and that is beautiful, but I think it is a mistake at that age to focus only on catching air. This is the same mentality that has older riders learning tantrums who cannot even ride switch. He can do tons of surface tricks and spins behind that boat with the right encouragement. For starters, make sure any removable fins are taken off his board. In this day and age, there is no point in having kids become dependent on fins only to later take them off and have to relearn. My son (8) has never ridden a board with fins. Also, it can be fun to set up a reward system with a chart, log book, stickers, or similar. Ronix kids' board a few years back came with a pack of stickers, and with each new trick a sticker was added to the board. This worked great as a motivator, and I expanded it with my own extra stickers for even greater emphasis on switch versions of basic tricks. Rewards can be given for counting out loud or saying a rhyme while riding switch, waving, touching the water switch, etc. Find language that your kid thinks is cool (e.g., my son thinks the idea of riding "cuffed" sounds tough, like handcuffs, so he's working on that). I'm not above bribes, so if he needs that extra push to try something new, then I'll challenge him to do it for a double scoop Baskin Robbins on the way home.
Your boat is not conducive to catching air, so why make that the measure of accomplishment? My son rides on Saturdays with my competition slalom crew behind a 196 with tiny wake, so we make the wakeboarding goals line up with the boat and the conditions. We do land training to work on eye and head position (eyes ALWAYS on horizon, knees bent, tug handle and press to the small of your back, etc). Years ago Mike Schwenne showed me a spin trainer he invented ($6 home depot lazy susan swivel sandwiched in between an old deck and a plywood base, then you attach a rope and handle to something solid, put a bit of bungy cord in the line for stretch), and let him spin his little head off on land. I made one and it has been helpful. I've also just dragged him around on the grass while strapped into his board to trouble shoot body position issues.
I do agree with whomever said get him out with other riders on other boats with real wakes, this will keep him motivated and also exposed to diverse instruction and influences. When we occasionally get up to the delta and ride sacked out, then it is a whole new exciting dimension, but the fundamentals are there. Now even when he is working on boosting air off a legit wake, he doesn't crash nearly as often because his board control and balance are so much better.
These are just a few ideas that have worked for me.
https://www.youtube.com/watch?v=fHI-...ature=youtu.be