That boat is a DS1, with a wooden bulkhead added at the cuddy opening by some previous owner. The forward bulkhead is in the same place as other DS1's, and yes it's about 4' from cuddy opening to for bulkhead. Your second setup is a DS2, a different beast entirely, as it has a false deck and bilges underneath. More on that in a moment...
Depending on the exact vintage of the boat, the DS1 has either a full forward bulkhead, a "shelf", or a shelf with a false bulkhead above with some hatches for storage. Your's appears to have the last option. The fore bulkhead is mostly there to hold foam flotation blocks, it's not structural. Note that I wrote BLOCKS, the flotation is nothing but big styrofoam blocks, which eventually (years) get waterlogged. So, right off the bat, I'd say you can take out the foreward bulkhead if you want and gain more space, but.... #1 you have to put the flotation somewhere! You could just reverse the order though, keep the "floor" clear for your son and put proper two-part liquid foam along the roof. #2 How much are you planning on being up on the foredeck? It does in fact flex, the support underneath is nice to have. That being said, in two seasons of sailing, I've been on my foredeck two-three times max. Of course, I have a jib downhaul, so no need to go forward while underway. However, with both those points in mind, I caution you that there is not THAT much useable space forward of the bulkhead along the deck, maybe 10 inches before it narrows too much. There's more room at the top behind the bulkhead, maybe 18 inches? Really not much, I don't think the "juice is worth the squeeze". As you photo shows, the DS2 puts the forward bulkhead further forward and therefore has less flotation foam. That's because the added flotation is under the false deck, not sure if there's foam down there, but there is at least a big bubble of air. Not much help if you're turtled, but that explains the smaller bow flotation. As I wrote, your're really not gaining that much.
AS GL wrote, let's attack the problem from the other end (like a monkey peeling a banana, right?). You want a space for your son, who I presume is small enough to get up into the cuddy? Then build floorboards and give him some soft stuff to lie on, he'll be fine. Also a good way to keep your things out of any bilgewater. The floorboards should be built to the level of the top of the keelson, and there are plans floating around online, I think on this site as well. You wind up with a space that it 4 feet x 4-ish feet, with sloping sides (the insides of the hull), overall it's like sitting under a dining table. I'm 6' tall and wear a size 48 suit-jacket, but I go under there for a sit when it's raining. A pain to get in and out, but otherwise a fine place to wait out the rain. I rarely use my floorboards, I've got two pieces of indoor/outdoor carpet that I use for sitting around (under cuddy, ashor for picnics, etc). Of course, I don't have that cuddy bulkhead so I can get down there when I want. Personally, if it were my boat, I'd get rid of it. Doesn't look watertight at all (huge opening), so what's the point? Now, for sleeping aboard, you have two options, you can either sleep in the cockpit, maybe with extra boards between the seats (make a sleep platform), or you can rip out the cuddy bulkhead and build a shelf going forward,. The later would be at seat height, going from the seat to the forward "shelf", rip out the forward false bulkhead (with the two little hatches) and you have your extra 12' of legroom. Check it out here, very last photo (and a great read!):
https://sites.google.com/site/dinghycruising/Either way, you'll need a cockpit tent, but that can be as simple as a tarp attached to the boom. The author of above article used an old pup tent, that works too. As GL noted, the next problem is where to put provisions and gear. As it used to say in my math textbooks, I'll "leave that as an exercise to the reader," but I'm sure you can be creative. Drybags are your friend! Beware that the DS does not like to be heavily loaded, it will sail but like pig. Then again, I'll take a sailing pig over a powerboat any day, so it's all relative. Overall, good looking boat, looks ready to sail and you can modify things at your own pace.
Good luck!
Tom