Input needed - Prone basing

Folks
My immediate plans when I first started this endeavour was to use 40mm round bases for prone figures.
However I've noticed that that does leave a lot of space around the figure.  I can make this look decorative on the base, but in the end it means that a given squad or section will take up more space that may be necessary and may look somewhat disjointed.
I am just not sure...
Below are a couple of pictures showing two prone figures on a 40mm round and a 20mmx40mm rectangular. Which do you think looks better?  Let me know in the comments!

Bases Arrive!

Yesterday my package of bases from Back-to-Base-ix arrived.
These are several hundred pieces of 3mm MDF in a range of sizes and shapes.

 Last night I sat down and liberated a sprue's worth of the RedBox Ikko Ikki from their plastic chains and stuck them down on 20mm round bases.  A nice fit I think. Tonight's plan is to texture the bases and hopefully undercoat tomorrow.

 Here is my plan for the WW2 figures:

• 20mm round for single figures.
• 40mm round for prone figures.
• 50mm round for weapons teams

Further steps

Today the parcel post guy arrived at the door with two packages.

One was some new larger trees from wehonest_cn on eBay (a great source of cheap trees) and also a package from AlwaysModel containing some RedBox Ikko-Ikki for Ronin.

I'm itching to get going; I just need those mdf bases to turn up and we can get this party started!