For a more concealed mechanism for the rear pins - this is what I did on my Hunter: http://www.rcuniverse.com/forum/fb.asp?m=3538275 - perhaps you could adapt that somehow.

For the spreading issue - on long hatches I usually use a combination - tabs as David suggested, and sometimes also a threaded pushrod that just connects from one side of the hatch / fuselage to the other (turning a clevis in or out a bit allows for adjustment of the "pull").