I had insomnia in the night, so continued a bit with this, and then actually left your intended design slightly (!) with the aim of showing you some more optimum edge flows etc etc... so below I have 'completed' the rear vent in just one of the myriad ways in which we could do that... that looks like this...
And breaking that down into stage, in case it helps you with yours...
Referring to following...
1. Beginning with the opening I made yesterday, first step is to ctrl-scale in a small loop to redirect the edge flow around that hole (yellow arrows)
2. Then I added some edge loops along the 'spike' to get more density there, and bridged from one side of the hole to the other (green lines)
3. Then I added those 3 loops (purple lines) with loop cut and moved those into an inverse curvy shape matching the outer side roughly...
4... which gave me 8 edges (red highlighted) I could then extrude back into the hull, and rotate the round the corner.
Lastly I did a round of tweaking in which I evened out and prettified all the edges etc etc, and then patched the end to quads with the 14 edges I had there.
Now I don't know if that is exactly the sort of vent you want there, but I figured it might be useful to you to see that approach regardless.
CBR