Painting tiles on top of map

I must be missing something really obvious. I could swear I've done this before, but it's not working.

I used Mange Tiles to paint the main map floor so it covers the whole canvas. Now I'm trying to place some other tiles on top of the map. I don't want to use Tile Painter because I need to be able to move and resize them. So I'm using Manage Tiles. But as soon as I select the Mange Tiles button, the main map floor turns yellow, and I can't paint any tiles on it. The only way I can paint any tiles using Manage Tiles is to make the main map floor smaller so I can paint on the empty canvas, then resize the main map back to full size again and finally move the tiles around as needed. Why can't I paint tiles on top of each other? Especially when one is the map floor?

 

Ah, just as obvious as I expected. Thanks.

 

Is there a way to hide tiles from the players without using Fog of War? Ideally I want the tiles to be visible to me but not the players. So I don't want to just plop other tiles on top of them, either.

 

Yes, but that makes them invisible even to me unless I have Manage Tiles selected. I want to be able to see the tiles at all times. I guess I could place them as invisible creatures instead, but I don't like them cluttering up my roster. I've had like 50 inactive creatures in the roster on some maps. Not a big deal, it just bugs me. That's why I'm trying to figure out another way.

 

I tried using Markers today. It did exactly what I wanted! The only problem is that the number images I have are apparently too small. Which is weird since they're actually 200 pixels square. But even choosing Large size in the Markers window, they are too tiny for me to see unless I'm zoomed in. Ideally I'd like them to be big enough so I can see them when I'm zoomed out far enough to see the whole map at once—it's a pretty big map. Is the Marker function reducing my images to some standard size or something? Or can I just enlarge my images to make the markers larger?