I do appreciate the responses. They give me food for thought. Its difficult to show how tight everything is stuffed under that hood. With pictures you loose perspective, both space and objects appear larger, and sometimes smaller then they are. Without a reference, its pretty hard to really judge the space.
I dug through some of the inbuild pictures of this truck, some of them may help.
QuickDodge,
Picture 1) shows the top of the firewall without the hood in the way. This is just before the removal of the old radiator. It was higher then the current radiator so the radiator hose connection is lower, but the top of the radiator hose remains that high where it goes over the top of the AC compressor (typical 5.2/5.9 Magnum upper hose routing). The two nut clips and the metal they are connected to at the bottom of the picture are still present. The hood center bolts to these two nut clips and also bolts at the top of the firewall near the wiper posts. The highest point on the red primed firewall is about 4" above the the top of the air filter housing.
Picture 2 is with the old radiator removed. I've added the in hose radiator cap into the upper radiator hose. it is the highest point in the cooling system, and where I have the current recovery system operating through. Two things to notice here, the curved bracket above the brake booster is the hood open support brace. That brace is two pieces, the straight piece at the rear of it connects to the under hood bracket and when attached, would be very near the top of the firewall/cowl. The 2nd thing to notice is the the top edge of the fender on the right side of the picture. It shows how much stuff is hanging on that fender edge. The only possible opening is in the lower right corner. What is not bolted to the fender in that area is the hood latch hook. With the hood latch hook bolted in place, I can not get my hand through that area.
Picture 3) this is the current recovery system. The overflow hose from the in radiator hose pressure cap travels under the radiator hose and is zip tied to the heater hose before it swings up to the bottom of the aluminum recovery tank. The gate valve in the heater hose it to shut the coolant flow off to the heater core through the summer. in this picture the valve is open. The top of the recovery tank is about an inch above the in hose radiator cap, and that cap is 16lbs (the only pressure they make for those small caps I'm told). The over flow for the aluminum tank comes out of the highest connection on that tank, and it goes over to the radiator hose, and is zip tied to it until it attaches to a metal tube that drops down to under the truck to dump. One thing to notice here, near the overflow dump tube you can see the hood latch hook bolted in place. For reference, that hook is 3" from where it bolts to the fender to the top of the hook, and the hook itself is 2" wide. The only open area along that fender edge is where the metal overflow tube turns down. That dump tube sits just inside of the frame rail, and from the top of the frame to the top of the fender is about 11".

I'm believing at this point that my aluminum recovery tank is about an 8oz cup short of having enough capacity. The system appears to maintain the coolant level at about 1/2 the diameter of the 6" long high arch of the upper radiator hose, but the recovery tank is empty. I don't like the idea that I need to take the radiator cap of to see the coolant level in a recovery system.

The possibility of putting an overflow tank in the location of the dump tube does exist. I can get an overflow tube tank that might fit in that area. Those tanks have an inlet tube that goes within an inch of the bottom, and a dump connector that only goes about an inch from the top. They have a cap on them, but it would have to tuck under the fender and that cap would be inaccessible. If I filled my aluminum recovery tank about an inch from the bottom so it would show in its sight glass when cold, then run the aluminum tank overflow into the inlet on the tube tank, then just dumped the overflow from the tube, would that maintain the level in the aluminum tank? My thought is that when the aluminum tank over flows, it would overflow into the tube, and when it cooled, it would suck the coolant back into the aluminum tank. I would probably have to maintain enough coolant in the tube to cover the bottom of the inlet tube. In my mind that would probably increase the capacity enough to maintain the correct coolant level in the aluminum tank.

I also think I'm going to lower the temp at which the radiator cooling fan comes on (it is adjustable). The truck does not appear to over heat, the fan only comes on when I hit stop and go traffic after a highway run. but maybe if the can kicks on a bit sooner, that might help. I had to remove the mechanical fan for radiator clearance.