My idea of the perfect rifle like the one you are discribing is one I built for myself to be my 0 to 800 yard packing rifle.
Here is a pic of it with the pronghorn I took with it this past fall with a 730 yard one shot kill.
The specs on the rifle are as follows:
Tured Rem 700 CM receiver
Lilja #3 27" 1-9 SS barrel
DE small diameter muzzle brake
HS Precision Sporter stock
HS Precision DM system
RB 1.5-3 lb trigger
Teflon coated flat black
Burris two piece DD bases
Burris DD signature rings
Leupold Mk4 3.5-10x 40mm FFP TMR reticle
7mm Allen Magnum chambering
200 gr ULD RBBT at 3150 fps
Total rifle weight is right at 9.5 lbs as you see it. Ballistically, there are very few rifles that will even come close to this rifle unless you go with a longer barreled 7mm AM or jump up to the 408 CT based wildcats. I have to use a BC of .880 with this particular rifle and load to get predicted drop charts to match up with actual bullet flight. So you can run the numbers on a .88 BC bullet at 3150 fps and see what it will do.
I can pack it all day long and did many days during pronghorn season including a 7 mile hike one day and the rifle was not a problem at all to carry. I am not a little guy, 6'3", 205 lbs but not overly large either. Any relatively in shape man could easily pack this rifle all day long.
The chambering was chosen for a couple reasons. Because its one of mine for starters!! [img]/ubbthreads/images/graemlins/grin.gif[/img] But also because its on the top of the pile for ballistic performance. Also, its windy where I hunt, all the time!! So a very high BC bullet driven to good velocities is a must.
A wildcat is not a requirement as there are many fine factory chamberings that will do what you need. If you do not want a brake, you will be wise to stay in the class of the WSM or standard belted magnum if you want rifle weight to be much under 8 lbs. If you are not opposed to a muzzle brake, the RUMs really become a fine option for long range packing rifles.
Accuracy wise, a rifle like the one above will not run with a semi heavy rifle but this rifle will easily hold 3/4 moa out to 900 yards. If I intend to hunt in an area where longer ranges may be a possibility, I will take a heavier rifle simply because they are easier to shoot at longer ranges. Not nessesarily more accurate, just easier to shoot accurately.
Optics wise, I feel for a lightweight rifle, the Leupold Mk4 3.5-10x 40mm is nearly impossible to beat. The NF scopes are great but not suited for lightweight rifles. This Mk 4 is very light and with the FFP reticle, it is extremely functional for long range hunting using the ballistic reticle for reference hold point in the field at any power range, something you can not do with a conventional scope with the reticle on the second focal plane.
Bases and rings, I like all steel personally for a lightweight rifle. The reason is because dimensionally, the rings and bases will be pretty small anyway, I like DD bases and rings and the Burris Signature DD rings are the best I have used. They give up windage adjustment but are strong as can be and with a scope like this you will have more then enough adjustment to get easily zeroed. With a custom rifle, there should not be much adjustment needed for windage anyway.
That is my idea of the perfect packing rifle that offers legit 1/2 mile reach yet can be packed all day long and as weather proof as you can get.