If you choose to make your own drawing tool, Ookakiba, this is the easiest way to do it.

First, with your Mike Schley map open, click the crossed hammer and pencil button ringed in red on the left. It will open the 'Select drawing tool' dialog, which shows all the drawing tools available for this style.



Click the Advanced button at the bottom, and from the list of tools in the left panel select a tool that is closest in behaviour to what you want from your new Ice tool. Here I have picked the 'Terrain Default, Desert' tool. Then click New.



A smaller dialog will open allowing you to name your new tool. I generally stick with the defaults and just change the name at the end (as shown) so that the new tool will appear in the same place as the rest of the terrain tools. Click OK.



So you have a new drawing tool for your Ice, but it's still showing desert fill (or the fill of the tool you chose to use as a pattern for the new one). Click Properties on the right above the image (1), and change the fill to be used to Ice_MS (2). Then OK the properties dialog (3) and Save your new tool with its changed properties (4)



Then you should be able to use your new Ice drawing tool just like you use any other drawing tool, though you will have to locate it each time by clicking the Hammer and pencil button.

I know that you already have an answer that you are satisfied with over on the FB group page, but for the benefit of others who might be reading this thread...

First ensure that you have exported a high quality bitmap of the map. in the "File/Save as..." dialogue you can do this by selecting any of the PNG options available in the dropdown box for file type (png files are better quality than jpg files), then clicking the options button and setting the height and width in pixels to at least 2 or 3 times the height and width of your map in map units. Set the ppi to 300, and antialiasing to about 30-50 %.

Then when you convert to pdf ensure you are using print quality settings - especially the ppi/dpi to 300.