Congratulations on your new move! I think that your son will be just fine. If he senses that you are apprehensive, then he will surely pick up on it. So you need to be excited about the move, but, don't go overboard. And I'll tell you why in a minute.
I would go to your library, or internet, and look up your new town. There is that site that will actually show you an aerial view of your rental! (I don't know it, but if you want me to get it I will ask my teen and get it for you). Look up the towns site and find places of interest nearby. Tell him about the park, the library, etc. Make it an adventure. Let him pick out the first place he wants to go when you get settled in.
I imagine that you might be putting some things in storage while building. I would certainly make sure he has his same bed, (not a good time to make a transition from one sleeping arrangement to another), I would put his same decorations up if possible, and of course lots of his "favorite" toys. If he wants to take them all and he cannot, pack some away that you know will not be missed when he isn't around. Then you can say, "we have "30" toys here and they will not all fit right now, so we will put them down for a long nap, (or something that you know will work with him). Now we can pick which ones we will take (or let stay up, whatever). Have him put 5 aside that he can bear to pack away. If you need to do more, than do it again. If it is too much for him, do it on another day. You see, this way he feels he has some control. And believe me, that will be his biggest issue!
Now back to my previous comment about not going too overboard on talking about the move. My husband and I kept telling our daughter how great preschool was going to be. She was actually the one that wanted to go, I wanted to keep her home with me since she is my last child! Anyway, I could see as time went on, the more we discussed it, the more she started shying away from it. I told my husband we needed to stop or she was going to be getting dropped off at pre-k crying, and no way would that work for me!
So we did back off, if she brought up questions we answered them without going on and on. And she did perfectly fine.
I've worked with kids in one capacity or another for most of my adult life, and quite a bit of my teens. I have found that the younger they are, the more resilient they are. You might have one or two bad nights at the new place, but then again, maybe not. I think keeping it low profile, adventuresome, and as least hectic as possible, is the key. And if you are going crazy with packing etc, get someone to care for him while you go nuts with all the work you have to do. Just make sure he gets to help pack!
Good luck!
R.
ps. I have 4 children, and believe me, if you want to get sleep, DON'T lay down with him if he wakes up calling for you. You can go in and reassure him, maybe have a cool flashlight by his bed that HE can use to reassure himself eventually. That way you won't get into that pattern of feeling guilty for moving him, which may cause you to lie down with him. This will become a nightmare, trust me, I did it! Make sure he has brushed his teeth, had his drink of water, (if you do that) and has had his nightly book. Maybe you'll want to have a book by the flashlight so that if he does wake up he knows he can read his book with his flashlight, but he shouldn't wake up the family, unless of course it's an emergency and you can explain those to him.