my submersible is built in a similar way, there is a tube, with an apeture in the rear, this is sealed by an o ring, the rear section is removeable...it also has a tray fitted to the inner face it with all the components mounted onto it, - so disconnect the rear section , release the o ring and simply slide all the internal out through the aperture....
so in simple terms.....
model is a static diver using the Norbert bruggen gummi sack principle-
model floats on the surface 50 % submerged with the gummi sack ( a flexible rubber water container) , pump on board water in to the gummi sack- model becomes heavier and down she goes, the gummi sack swells inside the body of the sub as it fills with water - compressing the remaining air left inside the body of the sub ( a sealed tube )
to surface pump the water out of the gummi sack into the lake, - model become bouyant and surfaces..the air insode the hull returns to normal ' pressure'
as my sub is short and not a 6 foot long brute, i have no front dive planes
on mine i have rear planes directly behind the prop along with a beefy motor so if i need to affect the angle of run once submerged i can do it pretty much hassle free with rear planes alone... or i can pump water in or out if i wish to go up or down ...
so its best of both worlds, having the ability to static dive if i so wish and using force to operate like a dynamic diver should i so wish...