I wrote iconic to solve this problem by letting you define a grid size larger than the icons. Additionally it will:

Allow you to move icons to any of three monitors
Not suffer the “lost icon syndrome” that occurs when monitors of multiple resolutions are used
Sort icons alphabetically, alphabetically with “Link to” prefix ignored, sort by modified date ascending or date descending
Allow different grid size (columns x rows) depending on monitor, EG more on 4K monitor than 2K monitor
Instant Test button for quick experimentation on column x row changes or reserved space changes for monitor left, top, right or bottom areas
Test button will last for x seconds defined by you, clear all windows before test and restore them after test
Bash script for easy modifications

You can get the script on github.

Here’s the main screen:

Visit the github page for iconic to see all the other screens, explanations and a copy of the script.