@RussC
You make some good points and I respectfully acknowledge that you have much direct experience with Mac 25 trailers than I do.
I looked really carefully at a zoomed I picture of the trailer...And it says Macgregor 25 on it! so it’s probably OEM.But honestly, I think that trailer is set up badly, even if it came from the factory like that. I’d change the bunks and get rid of the rollers, even knowing that the factory set it up that way. But unless the trailer is unsound in some other way, that’s not a deal killer, in my opinion.
I also looked carefully for any more forward cross members to support bunks, and there aren’t any. You can see grass where there should be a forward cross member .
In my 30 years of sailing with other trailer sailing clubs and owning my own trailer sailors, I’ve seen too many boats with damage from trailers set up like that (and I have owned and repaired a couple of boats with damage from badly setup trailers)
I always check the axle alignment and tongue weight every time I buy any kind of trailer. It’s a straight forward job to measure the total weight and the tongue weight of a trailer, and to adjust tongue weight, if necessary. Its straight forward to move the axles and or bow stop and shift the boat. (We did it on my most recently acquired boat using a tractor and a floor jack). Adjusting Incorrect tongue weight or axle alignment is just something you do once, and certainly not a deal breaker.
But I’m still very worried about such short bunks, ( at least as they appear in the picture), the lack of bunk support under the swing keel, and the limited visibility of the rear lights. Common practice for a sailboat trailer is that bunk support be around 2/3 rd of the waterline of the hull, but I’m sure there are some exceptions to it. I’d still advise the prospective buyer to know the cost to fix any short comings before he buys the boat.
There are also many instances and pics on the internet of deformation and cracks when bunks are too short. I myself have seen more than a few boats that had to be repaired due to point loading on a bow roller. I’ve seen examples of swing keels that were damaged because they hit an axle or crossmember but I have never personally experienced that. A bunk from the back of the frame to the front of the swing keel or further prevents that kind of damage.
(I installed a center bunk under the swing centerboard on my current boat that came with the original 1992 trailer. The previous owner used to stuff some padding under the keel and over the cross member to prevent damage. Seemed like a crappy shortcut of a solution to me.)
Judy