Pages -changing document size and formatting tables

[macstatic]

I've got a couple of Pages (8.1/MacOS 10.14) documents which consist of tables that have many columns. This in turn means a wide document -which isn't a problem since I don't intend to print it (exporting to PDF and viewing it on the computer is fine), so I can choose a wide paper in the "Documents" section.
But... it's not wide enough (I'm currently using "A3 (borderless)" and can't seem to find anything wider. Is it possible to create my own custom paper size?

Regarding the tables I have a problem with cells not being wide enough for several items, while for some items they're wasting empty space. I suppose part of the problem is what's already mentioned (paper size), but is there a way to fix this (other than manually resizing every single column)?

 

[HobeSoundDarryl]

Tabloid paper size is slightly wider than A3 in landscape mode.

Apparently you can create your own paper size. And I just confirmed that those steps work.

Select Table, Table tab, under Row & Column Size, click the "Fit" button next to (column) "width." That should size the width of the columns to fit content probably better than it is now.

If you still need better spacing within the cells, Text (tab), Layout, cut Text Inset down to as little as 0. Then back to "Style" and perhaps horizontally center everything... then back to "Table" and again click the "Fit" button next to (column) "width."

 

[macstatic]

Tabloid paper size is slightly wider than A3 in landscape mode.

Apparently you can create your own paper size. And I just confirmed that those steps work.

Awsome! Thank you!
I don't know why I at first couldn't get this to work here, but then I tried to change the printer to "Any printer". After doing that, all the custom paper sizes I'd already created appeared in Pages!
(I've set up my Mac for multiple printers because the laser printer only prints in black/white, so I needed to install another printer driver in order to "Print" PDF files in colour. I've created several alternative "Paper" sizes for the sake of "Printing" PDF files out of websites, which usually look a lot better with slightly wider than normal paper sizes and a lot longer so the content doesn't get broken all the time).

Select Table, Table tab, under Row & Column Size, click the "Fit" button next to (column) "width." That should size the width of the columns to fit content probably better than it is now.

If you still need better spacing within the cells, Text (tab), Layout, cut Text Inset down to as little as 0. Then back to "Style" and perhaps horizontally center everything... then back to "Table" and again click the "Fit" button next to (column) "width."

That, in addition to first changing the paper size above, to a much wider landscape orientation than now helped, but it looks like I might need to adjust the table cell sizes as well by clicking on the table, then dragging and resizing the columns and rows.
I figured out that it makes a great difference if I select a column's contents to "Wrap text" or not -perhaps obvious, but confusing to find the right combination of all these settings to make it work