I have a Remington Mtn. rifle with the aluminum alloy trigger guard assembly. I have hunted with the gun for 11 years and unless you are planning on using it for an axe or a shovel I fail to see a problem. Sure its not steel but its also not an 8 lb. rifle either.
For an option check out a lower end Savage 110 series rifle, their trigger guard is plastic.
I have never seen a "three piece" bolt on a 700 series Remington so I need educated. I have Remington rifles made in the early sixties right up thru an SPS and a VSSF made last year.