URT wasn’t a success for many reasons but partly because it only works when seated and lots of people stand or unweight their saddle and still want suspension to be active. Having it lock out when you stand means you’ll not get the benefits of increased traction and tracking that suspension brings.
I once did a URT design that had the pivot just behind & below the BB as opposed to the usual above and in front. The thinking was that the difference between seated and standing would be reduced but I’d get more travel on bigger hits where I naturally stand or unweight the seat in faster rockier areas and less travel / tighter suspension when seated and pedalling in smoother slower areas. Kind of like a hardtail with big hit capability.
Increasing the tension in the bottom run of the chain wouldn’t make much difference. The force carried in your chain is between the pedal and the ground, through your rear wheel, not so much the whole chain as a loop.
