how should i set up my O-line?

https://www.mut.gg/24/lineup-builder/dc40e6e8-64db-484f-ba4b-06191ecf5c0d/

I was thinking putting Slater at LT, move Thomas to RG, sell Seumalo, and keep Whitworth at RT. All are BND except for Seumalo.

In my experience and I think this is the general consensus in madden (and in the NFL), 

O-tackle, especially left tackle, is more important that guards, especially if you have a good center. 

Seumalo will go for less than 80k so unless you are in huge need of a few coins, I would keep your O-line where it's at right now.