Hi Biggs,
Let me start by saying that is a fine job on the Main Mast!! Clean and straight!! Well done!
Okay...figuring out what "we" can come up with to correct this unfortunate issue. Well, I am not and expert by all means and before I wanted to respond here I had to look into a couple things.
First was the kit parts. As you probably noticed, the PE and the kit parts do not match up. The PE is slightly larger. Best I can tell at first glance is that the Range Finder Platform (1st on the mast) defines where the supports go since it forms a triangle. So, first suggestion we could do to correct this would be to not use the PE RF platform and use the kit supplied one. This would drive the legs back in and most likely hit their mark.
A decided to take some time a short while ago and look at the plans. I superimposed the DML Main Deck and Superstructure deck section onto the plans.

We knew the kit would not match the plans when scaled together but by lining up the aft support of the main mast, both of the crane support holes lined up fairly close. We can see the front supports don't line up.

The blue dots outlined in red are the original, and the faint yellow the kit. Even though they do not line up there looks to be a way out of this....
I am thinking we could cut off the over-sized over hang where the supports go through the kit deck. (shown in the red lines above). This should cut off the holes popped out of the wood decking nicely. On the actual ship it looks to be that the support come down along side the Potato peeling/vegetable room located on the print. I put a line where the rear wall of the upper deck is actually suppose to be...

The support you have now would hit the yellow dots...or close to.

A small scratch built wall on the underside of the superstructure deck would eliminate trying to cut the bottom of the mast support on an angle against the back wall. Only problem you have after all this is making the mast supports you have already installed, longer. Gluing extensions is one way I suppose, or dismantling the mast(which I know you probably do not want to do). I would try gluing extensions first.
For reference purposes...


Sorry about going on with this...kind of how my brain has to work to figure out stuff like this when it comes up!! Now I need to step things up if I am going to catch up to you!!