What size linear rail ?

Hi all,

I'm trying to finalize the layout for a router table.

Looks like it will be based on a 1/2 thick steel plate as the base
and be roughly 30" x 40" square.

in looking at linear rails it seems they start around 15mm wide and
go up in size (and price)

The main use will be to cut out shapes in 1/8 thick aluminum with a
router.

The 15mm stuff, per McMaster Carr has a dynamic load rating of 1,872
pounds. But the size just seems to be too small.

Anyone have any guidelines or recomendations on what size rail would
be best ?

Dave4