Having an auxiliary dock in the mothership's exhaust isn't all that unusual ITRW. Quite a few warship types deploy auxiliaries from a stern ramp into the propwash, say, or receive their helos with a blast of hot air from their own turbine exhausts.
Would there be advantages to having a stern-facing docking port? It's interesting how so many starships have stern-facing shuttlebays for some reason. And shuttle approach then necessarily means diving into the impulse exhaust or, considering common nacelle placement, into the very heart of the warp fields, to no evident detrimental effect.
It's not as if the impulse engines would shoot out flames or jets anyway. They appear to be more like radiators, not suffering one iota if the ship's own structures block the view directly aft of these tailpipes... Perhaps standing next to one is not particularly harmful under any circumstances?
All that said, the issue of aft torps on these ships has always been a controversial one. I really liked the ENT take on this, in "In a Mirror, Darkly", where the torps fired from a spot fairly low down, apparently on the dorsal surface of the secondary hull. But torp tubes appear to be easily movable in a refit, as we see in ST:TMP...
Timo Saloniemi