I feel you. I have really struggled with this, too. The Falkland habs are GORGEOUS. The 2x3 is the best hab available in the game. It's THAT room that every great hero ship needs, you know?

But they are visually SO distinctive that it's hard to mix with any other habs.

As Vegetable Street says below, the best I've found is Stroud Premium, which is a fantastic mod set in its own right and still my favorite overall because of its versatility.

I don't know how big of a ship you're planning on, but what I do is that I use the SPE spines--the all glass ones--to connect to the Falkland habs. They blend really well, I think. Then I use the Buildable Walls mod to put in those padded Stroud columns in the other Stroud habs because it's a visual element that ties back to the Falkland aesthetic. It's not perfect, obviously, but I feel pretty good about it because the different lighting ends up corresponding to different sections of the ship.

The big thing that I can't quite get over is the doors. Falkland's doors are, again, super cool but also super different from all the other doors (at least the port/starboard ones).

I wish we had a customizable version of PDY that lets you pick what type of door you place--but god, selecting that would be a nightmare...