Straps for super tele lenses

What strap do you use for your super telephoto kit?
I have a Sigma 120-300mm f2.8 lens. It’s a bemoth of a lens and when combined with a body the total weight is over 4kg. Most often I carry the kit in a back pack until I want to use it, but then I hand carry the kit by the tripod mount of the lens. This less than comfortable over long periods!
I note that the tripod ring has lugs for a strap to be fitted, but I am wary of applying a strap such as an optech as whilst these are ok for weights up to 6-7kg (depending on model), I worry that the forces applied when carrying the lens may exceed the maximum specified (e.g. a small jolt may effectively increase the force beyond the tolerance of the strap). Combined there is nearly £6k worth of kit at stake and dropping this would likely break my heart.
So what strap solution can you recommend?
Adam
I have a Sigma 120-300mm f2.8 lens. It’s a bemoth of a lens and when combined with a body the total weight is over 4kg. Most often I carry the kit in a back pack until I want to use it, but then I hand carry the kit by the tripod mount of the lens. This less than comfortable over long periods!
I note that the tripod ring has lugs for a strap to be fitted, but I am wary of applying a strap such as an optech as whilst these are ok for weights up to 6-7kg (depending on model), I worry that the forces applied when carrying the lens may exceed the maximum specified (e.g. a small jolt may effectively increase the force beyond the tolerance of the strap). Combined there is nearly £6k worth of kit at stake and dropping this would likely break my heart.
So what strap solution can you recommend?
Adam

Have a look at Black Rapid straps. They supported my 5Diii + 70-200 f/2.8 without a thought, and I'm pretty certain they support up to 7 or 8 kilos. Plus they are very sturdily made and it would take more than just a nudge to dislodge equipment.
Worn cross-body, I was comfortable carrying it all day.
Worn cross-body, I was comfortable carrying it all day.

A cheaper version is the Trekking Safari Pro Plus Camera Harness which is nearly half the cost of Blackrapid https://www.amazon.co.uk/Trekking-Safari-Plus-Camera-Harness/dp/B00LM3L936
I bought one at the NEC Photo show, but cannot give any feedback as not had time to try it out yet.
There are a couple of versions but liked this as it also screws into tripod socket for added security.
I bought one at the NEC Photo show, but cannot give any feedback as not had time to try it out yet.
There are a couple of versions but liked this as it also screws into tripod socket for added security.

https://www.jackthehat.co.uk/trekking-safari-classic-camera-harness-12312-p-849.html
I've used this Trekking harness for about 5 years now and it's still going strong.
I have the chest strap tight, the camera connecting straps hold the camera, and the tripod foot hooks over the chest strap so the lens lies across you chest and doesn't swing about.
I carry a Nikon D500 with the Sigma 150-600mm Contemp. like this.
You can get spare straps for other camera bodies, and an ordinary camera strap that fits the clips making it a versatile set up.
Although Jack the Hat sell via eaby and Amazon things are slightly cheaper if you buy direct from them
I've used this Trekking harness for about 5 years now and it's still going strong.
I have the chest strap tight, the camera connecting straps hold the camera, and the tripod foot hooks over the chest strap so the lens lies across you chest and doesn't swing about.
I carry a Nikon D500 with the Sigma 150-600mm Contemp. like this.
You can get spare straps for other camera bodies, and an ordinary camera strap that fits the clips making it a versatile set up.
Although Jack the Hat sell via eaby and Amazon things are slightly cheaper if you buy direct from them

An alternative is not to use a strap at all, and to carry longer lenses, along with camera body and other lenses or converters, in a well padded "single compartment" back-pack.
Several of these types of bag have straps to fix a tripod and a mesh external pocket for a water bottle.
With the back-pack harness adjusted to split the weight between shoulders and hips I can confirm you can carry a lot more weight a lot further with this type of bag.
With the bag on the ground and open you have quick access to other lenses, converters etc.
Cost new is from about £250. Expect around 10 years wear from a robust back-pack.
Several of these types of bag have straps to fix a tripod and a mesh external pocket for a water bottle.
With the back-pack harness adjusted to split the weight between shoulders and hips I can confirm you can carry a lot more weight a lot further with this type of bag.
With the bag on the ground and open you have quick access to other lenses, converters etc.
Cost new is from about £250. Expect around 10 years wear from a robust back-pack.