NEW BOAT TRAILER
I bought a Karavan trailer a number years back after my axle failed on my old 14.5 ft Starcraft. My observations:
1: Weight Capacity: tends to be low, does not allow a lot of extra weight to be carried on the trailer beyond the boat and motor. Not a big deal for some, but I prefer to pack my boat when we travel and keep the weight off my pick-up.
2: Trailer Height: The Karavan I had was quite tall for a bunk, making launching more difficult in shallow areas. The Shorelander I currently have on my 1950 Lund is much lower than the Karavan I had on the 14.5 Starcraft.
3: Bunk Lay-out: I haven't looked at one lately, but the Karavan did not have as much flexability in this department. I spent a lot of time trying to get it right, it never was perfect. Possibly plan on adding side guides because of this, as centering is tough if the main bunks don't help guide it correctly.
4: Overall Quality: Very basic, lower cost accessories, hardware, and lighting. It worked, but was not real high quality in my opinion. The bunks warped rather quick, not sure if the lumber was 'Marine Grade'.
I've had Shorlander bunk trailers on my last two boats, a 17.5 and my current 19.9. Both of these trailers were of higher quality, low slung, provided good support and centering, and had ample weight capacity to allow loading of the boat for travel. They would cost more however. If you launch a lot, and are keeping the boat for a while, it may be worth consideration.
Give them a look and decide for yourself. Never hurts to see what is all out there. Good Luck.