I just received one today also, along with a fith wheel I requested a week ago for one of my trucks, free of charge. They have great customer service. Makes you want to keep buying their kits.
The more I see this kits, the more I like them. I've done like four of these. One suggestion if I may, you can remove the sprue around the sleeper step.
I bet this is one of your best projects because you did it with your grandson. And it looks good too. Do you have the fith wheel? I have a spare one if you need it.
Man you are multitasking! I'll follow this build. Coincidentally I pulled the same kit from my stash last night. Gatorfan69 (Mack) posted a Rubber Duck build last night and that inspired to do one using this kit. Not 100% accurate but close.