RE: hull opening.
The problem with the HL system of screws is that if literally "sucks" the two halves together which provides part of the rigidity of the hull. If you don't use the screws, you need to build a support system that provides for the rigidity of the hulls. On my KT, I found out the hard way that once the screw post were removed, the hull flexed in odd ways which created a real hassle in building a rigid system.
With the two door cabinet door magnets locking the back down (I have to literally push and lift up as the magnets provide such a strong hold), I used the two front screw post for upgraded hex screws. I don't need to use the screws for normal operation, but it really locks the hulls together.
With Heng Longs, one thing always seems to lead to another....
tjs