If you wanted to float it, I'd have one end up onto the
boat and only worry about supporting the rest of it. But I'd be worried about getting it that wet and salty. Depending on how much support it needs (or doesn't) in the middle, you might be able to tow the
dinghy behind the
boat (with a backup tow line) rigidly attached to one end of the
mast and the other end of the
mast attached to the boat. I'd be worried about any kind of rough
weather with a setup like that, however.
As far as putting it over the top of the
deck house, you a that vertical piece coming up off the crossbeam in front it looks like. I'd expect you could make a simple
wood box with a slot in the bottom to sit on top of that and support the mast there. And you have
davits behind the
cabin top, right? If so, you should be able to use some
wood to make a bridge between them and support it there. That should get you at least 40 feet of supported length, I think (from looking at the drawing). Basically it would be supported over the cross beam, some chocks on top of the roof, then supported above the
davits.
If you run it along a
hull (and
dock only on the other side), you could get more than 40 feet of supported length, as you could build a support down to the lower step at the end of the
hull to provide support as far aft as possible.
Deck camber could be accounted for as well in the supports, you just use shorter ones in the middle and taller ones towards the end.
But if you were to carry it on the boat, I think along the centerline will be easiest to live with, as it won't be in the way of you moving around the boat. And if you can keep the forward overhang reasonable (and have a bit more overhang aft) it'll be easier not to spear it into things when
docking.