I picked up what I thought were the correct baseplates for some #3 longsprings. When clamped on, they are quite a bit longer than the trap base. Width is not an issue. Should I trim the baseplates to be the same length as the trap frame base?

I would. The ends sticking out would be a place for the chain to get wrapped up, eliminating the function of the swivels. And the OCD in me wouldn't be able to stand to see those ends sticking out.

It looked odd to me also, but then I remembered the older style traps with split jaw posts. The bases on them all stick out past the posts, under the spring eye. So in that respect, it does look a bit old school.

The chain getting caught on the ends sounds like a concern though. These will be land traps, not water.

The ends sticking out would also make them trickier to set over the knee, not being able to break the springs over at all.

Might also make the trap harder to set over your knee.

Just added that, yep.

These are getting installed, trimmed or not. No way am I ordering replacements.

…. Alright let’s see here … you got baseplate that are too long

… so what you’re gonna want to do is … get a tape measure…. Measure the length of the trap base

…. Then make a mark on the baseplate at that same length

… then cut it at that mark

… let me know if you ever need help with anything else… like which direction to go when tightening a nut or something

Actually, I marked the length of the trap base on the baseplate with it in place.
That way I cut an equal amount of both ends, not just one. That leaves the D ring centered.

Do us Yankees have to fix everything you do?

…. Attaboy lol

… I would have made one cut and made the d ring off center though

… you just messed it all up lol

You must be running some deliverance looking traps. Coyotes probably die laughing when they see you setting them ugly things.

… you got to offset the d-ring …. It’s an old secret I just let you in on

…you just can’t use one within 500 miles of Coldspring TX

I’d cut it short 1/4” on both ends. It’ll make for a easier cleaner weld

this^