There is no one that can convince me that a Hensley or ProPride VPP hitch is equivalent to a goose neck GN or 5th wheel hitch when it comes to handling.
Don't forget the PULLRITE, likely the best of the bunch.
As to "being convinced", you'd need time, miles -- and plenty of high winds -- driving both kinds.
On the "sail area", part of that is the flat front of a GN style trailer. I should have clarified that. Open framework is worse for aero purposes. Though I would agree that a well-designed trailer with 5'er or GN hitch could be done with good aero when matched closely to TV.
Ease of hitching is a non-starter.
There are still no advantages accruing. If one wants a heavy-weight aero GN trailer then starting with an existing A/S is not the way to go.
The thread by RoosterBooster
on PIRATE 4X4 does explore this concept with an A/S 5'er toyhauler
before discarding it, and he's a good read in any of his threads. His latest is on a Spartan.
over on ECOMODDER is planning an aero 5'er to go with his Dodge CTD. I think that discussion -- preliminary, with sketches -- may be more of what you're taking aim at; both here
I linked in several trailers, both an AVION
and Silver Streak
5'ers (they're also linked in this forum).
But none of this has anything to do with a trailer that, by design, was meant to be pulled by the family car delivering stable, reliable and economical performance over the long haul. Good engineering means "no more than necessary". A designed from scratch GN trailer, using an A/S shell on a framework sufficient to use that hitch is more than just a tongue replacement, but a substantial and heavy
is a 14k trailer, yet it would likely have better aero than a GN-conversion A/S.