PTG canoe style bottom metal will allow you to get 3 down easily in a BDL. Make sure you get the right mag box length. I've put these in every 700 I own/have owned. https://pacifictoolandgauge.com/141...-well-canoe-floor-plate-bottom-metal-bdl
I think you'd want to go 20-21" with an Omega, unless you want a very long rifle. A 20" 7mm mag will definitely beat a 20" 7-08, by a lot.
I have a handful of suppressed WSMs with 5" cans and 22" barrels. Longer that this and they get pretty unwieldy but everyone has their own standard.
Why not suppress the Beanland? Just about all my rifle cans are hung on either sporter weight or #2 barrels. I have a suppressed model 7 with a 7" suppressor on a factory pencil barrel (though it's short). No impact on mechanical accuracy, some improvement on practical accuracy, especially on the magnums. The Model 7 barrel looks like a sewer pipe inside but still shoots 120 NPTs into .4 Moa with a 7 inch can. If I put a 9" can on it, accuracy drops to 1moa--not sure if its the weight or the longer lever, etc.
You have plenty of options.