The V-nose configuration has no empirical data supporting "ease of towing" nor any "fuel efficiency" claims and most advertising is deceptive in how they lead people to believe that it does. The drag on your vehicle combination is a compilation of many factors and the V nose shape is just one of those factors. The modern "curve" of the fronts of most travel trailers is just about as effective in cutting the wind as a V nose. The V nose, if there are any advantages in towing, certainly doesn't change the physics involved
Weight is weight, and in that arena, the V nose is actually a hindrance in most cases.
If you look at the advertised weights for the V nosed V19FK, the dry weight is 3873 (it will actually be several hundred pounds more as it doesn't include a full load of LP nor battery and other "options"), yet the tongue weight is already 625 lbs (will actually be over 700 with the above LP and battery). The V19FK is very "nose" heavy; all of the "heavy stuff", kitchen and slide are forward of the axle assembly. Not uncommon with V nosed trailers, virtually all of them have the kitchens in the nose (the kitchen is easier to configure into that weird "V" shape without a lot of wasted space). If you look at that floor plan very carefully, you will see that in addition to all the "heavy hardware" being placed forward of the axles, all of your storage space for the heavy items you will take with you is also forward of the axles; kitchen supplies, food in the pantry, etc. I, truthfully, would not be surprised to see hitch weights exceeding 800 lbs with that configuration. You've also got at least one tank that would be forward of the axle (I'm guessing on that given the configuration), but, if you don't tow with anything in the tanks, that becomes less of an issue.
The 189FDS, on the other hand, has a dry weight (again, it will be heavier when the LP, battery and "options" are added) of 3040 lbs, but, a hitch weight 200+ lbs lighter
than the 19FK model. The 210WBS has similar specs (to the 19FK), but, since I own that particular model, I'll give you my "real world numbers". Ready to roll on the highway, my 210WBS comes in right at gross; 5,928 lbs (+ or - a few lbs) and my hitch weight as measured yesterday with my Sherline scale (we're leaving on trip on Sunday) was 737 lbs. A far cry from the "advertised" hitch weight of 395 lbs for that model.
As a "rule of thumb" figure 1200 lbs more than "advertised empty weight" to allow for options and reasonable loading of the TT and at least 300lbs more of hitch weight, again for options and loading. Also keep in mind that the best stability for towing a full faced RV is going to be a tongue weight of 10-15% of gross trailer weight with ~13% being the sought after "norm".
As for your Ridgeline... It will be actually be borderline for any of these trailers. While it may be "touted" as a fine tow vehicle, and it may well be (I've never towed with, nor owned one), with a 5000 lb rating it is going to be borderline for any of the mentioned trailers when they are loaded for the road. You've got a V6, and yes, Honda makes a stout 6, it is still just a 6 cylinder engine. You don't have the rotating mass (inertia) of two more cylinders to aid in torque, and torque is what moves a trailer. Your payload is also rated at ~1500 lbs. That's total payload...that has to include options on the truck, passengers and cargo. With ~700 lbs of hitch weight, plus, another 70-100 lbs for the weight distribution hitch itself, leaves you around 700 lbs for passengers, cargo and options. If you look closely at that 5000 lb tow rating, at no time do they say or show a full fledged RV with those weights being towed (the ad on the Honda site actually shows a boat being towed
. While the truck may be capable of towing 5000 lbs, that 5000 lbs that it was rated for was a low faced utility trailer with cinder blocks (concrete) stacked on it. Most advertised towing in the 3500 - 5000 lb range is aimed at boats, utility trailers, motorcycles, personal watercraft, etc. and not RVs. A "full faced" RV has a huge sail area and wind resistance, V nose or not, and is much different in requirements when being towed. Try some experiments with your hand out the window next time you are driving...wind resistance on a closed fist vs. wind Resistance on a full open hand... I tow my 210WBS with two vehicles. The 3.5 ton Jeep Commander with a Hemi pumping out 363 HP, rated at 7200 lbs towing, is adequate for my 210WBS...I know the trailer is back there all the time and it is not unusual for me to pull at 4,000 rpms on grades >6% (the peak horsepower/torque is at 4100 rpm). My Ram 2500 HD with the high output Cummins Turbo Diesel (800 ft lbs torque), doesn't even know the trailer is there.
Can you massage the numbers so that you can tow any of those three trailers with your Ridgeline? Yep, but, though the numbers you are looking at aren't lies, they don't speak to the real world numbers you will encounter when towing, they all have to be taken in context and with a close eye to how those numbers were derived. I believe, though, that for safety, comfort and longevity of your Honda, you'll be better off with the 189FDS of the three that you mentioned.