I think about a "What if plane" let your son draw it and you keep it alive!
I think that would be great for you both!
Or inspire it to his favourite aircraft!
Third option is when the Bone will be ready,do it a simple version for him,like the B-1R,is a project,more AAM's and more fun for him,add multiple gunpods and you do his mighty fortress,the same of his dad!
I'm very close to You FC,and to anibody have this kind of problems,generated against their will,that's nobody's fault!
My Dad came back today from hospital after one month of complete isolation for a spinal transplant,doctor says that he must stay in hospital for 2 months,after only one every parameter is set to normal,It's like a little miracle!
The force of his mind can torn mountains in two!
I know that these problems are different,your son is healty and he's simply SPECIAL!