Short Steep or Long gradual

i would take the short steep way. I hate long gradual hills they kill your milage.

Steve

My daughter went to college in Lynchburg and I lived at the time in WV and used each of those routes many times towing her horse trailer many times with a Chev diesel with no exhaust brake---I 64 no question!

I would not go rt 60, I would go 220 to Roanoke, then 460 to lynchburg.
I have used all three routes, like 460 much better.

I would take the less steep downhill route even though it may be long. The 7.3 diesel will not hold you back much at all without an aftermarket exhaust brake so you need to start at the top of the grade very slowly in a low gear and use your truck and trailer brakes off and on to keep the speed slow. Don't let it build up on you.

I had a Ford 7.3 for years (2002 - 2016) and it was a great motor for reliability but not so much for power compared to newer motors. I also added an exhaust brake for a couple of years but it failed twice so I disconnected it and never had a problem descending grades as long as I did as described above.
Barney

The stress and strain of steep makes me worry about things a lot more expensive than brakes. I take the gradual every time.

Maxed out towing isn’t fun. RVing should be fun. Fix the issue.

If you don't have get an exhaust brake and don't worry.

On a long downhill grade, select a low enough gear so that you touch the brakes only once in a while. (And turn on those flashers when driving less than 50 mph.)

Make sure that the trailer brakes are properly adjusted.

Take the easiest route with the least amount of steep downhills. and

Use your gears to descend the hills. Here's a test with no towing involved. It's merely to see what gears you can use at what speeds.

Go driving with just the tow vehicle and no trailer. Go find a bit of road that you can accelerate to 60mph without endangering yourself or others.
Safely stop the vehicle and pull the shifter down into the lowest gear. Accelerate until 15 - 20 mph and then shift up one gear on the shifter.

Can you drive 60 mph in that gear without getting within 500 to 700 RPM before the red or orange markings on the tachometer? If not shift up until you can drive 60 mph while still being below the red or orange markings on the gauge. The idea is to find the lowest gear (2nd, 3rd, 4th, fifth etc) that you can drive at 60 without letting the tachometer get to the orange or red markings. Once you find this gear you know that you can downshift to this gear on a hill and not damage your engine.

Let's say your truck is like my Suburban that I can run 65 mph in 2nd gear without hitting the orange or red marks. When I crest a big hill like the grapevine I just use the brakes to slow down to about 50 mph. I then shift the transmission selector to the 2 position and take my foot off the accelerator pedal and away from the brake pedal and just start to coast down the hill.

As I go down the hill the speed will slowly start to increase. But, since I'm in 2nd gear it behaves like I have my foot on the brakes which I don't. When the speed climbs up to about 58 mph I put my foot on the brakes and firmly press to slow the vehicle down to 50 mph again. Once I get to 50 mph I take my foot off the brake and start coasting again.

I usually only have to touch the brakes three maybe four times for a hill the size of the grapevine. While it may seem like this is stressful it is usually just the opposite. With the transmission in a lower gear I don't have to watch the speed like a hawk. Instead it just goes down the hill as if I'm dragging a parachute behind me and only speeds up slowly

First thought? Make sure your brakes are in good shape, baby them so you don't loose them.