Question on THK

[Drools]

I currently have an 80/20 based moving gantry router. The X/Y axis use CNCrouterparts carriages with a movement of 22"x32".
I have 6 x THK SSR25-XW linear blocks and 2 42" lenghts of rail for the blocks. The description for these blocks are this:

SSR25 The compact design with a low sectional height and the ball contact structure at 90° in the radial direction make this model an optimal model for horizontal guide units.

Load rating can be found here.
https://tech.thk.com/en/products/thk...th.php?id=1107


My design uses the 1530 series of 80/20, I was thinking maybe I should replace the longest lenghts of 1530 with 3030 so the THK rails could be mounted to the top of the 80/20 with room for the spoil board between the rails. This would cost ~150.00+ for the 80/20 or maybe I could mount the THK rails to the side of my 1530 and purchase some 6"x1" Ali to use as the gantry uprights. I have heard someone say in the home hobby world we would never reach the load rating of these THK rails. Should I hold out and purchase 2 lengths of 3030?