I hang my 7yo from the same trees I'm on and under the same tarp. Every now and then he climbs into my hammock, but usually I just put a hand on him if he starts to get restless and it settles him down. Might be worth trying it with your son at home a few times so he can get comfortable with it, then see how it works in the field.
At worst, he'll sleep with you in your hammock...not a huge problem with my 7yo, but YMMV of course.
P.S. Unless you're using a HH, I guess...forgot about that. I've been in homemade Speers w/o bugnet.