Weight relationship between tripod & camera

[Cage]

My current tripod + head weigh 4.7 Kgs. My camera + 300mm lens weighs about 2.3 Kgs.
That's 7Kgs, or around 15 pounds, and after carting it around the scrub for a couple of hours it is getting bloody heavy, and I'm not getting any younger. BTW, it is rock solid.

I've been looking at lighter tripods (Carbon Fibre) and mag alloy ball heads, with a combined weight of around 2Kgs. I can't do much about the camera/lens weight, but shedding 2.7Kgs from the support system weight seems like a quantum step in the right direction.

In my internet wanderings I've come across a couple of articles by people who seem to know what they are talking about, and they quote a 'rule of thumb' that your tripod should be 1.5-2x the weight of the gear supported, with an addendum that the ratio may have decreased with the advent of lighter and stronger tripods.

Gawd I'm getting so confused. I need to shoot off a tripod because of unsteadiness in the hands and arms (Tennis elbow among other things) so I would really appreciate any info on this aforementioned load/support ratio.

It seems to me that all the ability and technique in the world won't cover up the shakes, and I'm not insinuating that I have even a smattering of either.

Cheers

Kevin

PS: I'm looking at the Manfrotto 055CXPRO3 + maybe the Markins Q3 Emille, both of which have a load rating of 3 to 4 times the weight of the gear I'll put on top.