So, if one accepts the ratio, wouldn't that restrict overall touring weight, vis a vis typically light weight ratings of front racks? Not that that's a bad thing....

no, these are not laws of touring. just general guidelines that some people find useful.
you need to try out various setups, learn what works best for you.

You can search here on bike forums and find that Many people prefer putting the bulk of weight in the front, down low. It makes the bike handle better and reduces stress on the rear wheel. Typically the rear wheel is carrying most of the rider's weight. Assuming a rider of 150lbs+ for the Vast majority of tourers, unless you have 100lbs or something Crazy on the front rack, you're still at a rear weight bias even putting most of your gear in the front. Rear racks ride higher, which makes the bike handle worse. Combine that with their thin stays/supports and length of those stays, and you get a lot of flex. Your rack is going to sway around with a lot of weight on it. Again, that results in poor handling. The front rack is bolted directly to the fork, and down low. As for the limitations of front racks, there are plenty that will handle 20lbs+. Personally, I wouldn't suggest carrying more than 40lbs of gear, so it would be difficult to carry more in the rear than the front will handle. Many of us try to stay under 30lbs of gear(and plenty stay under that, though I tend to be toward 30 with food).

Thank you! If and when I hit the road, I don't want broken spokes on my list of omg's....

My first tour was across the U.S. west to east. My wheels were not up to the task, so I can say that chronic wheel problems suck big time. Finally had the rear wheel replaced in Ohio when cracks were discovered around the eyelets. Discovered the same cracks in the front wheel before my second tour.

Hmmmm, most reviews (unqualified) indicated my Sunrim Rynho Lites are "bombproof".... Hope so.... What caused the cracks?

check the labels.
way back when they made quality rims, the labels said "made in usa."
then they started using cheap chinese potmetal, new labels say "designed in usa."

Tour was in '99. '98 Cannondale T700. Sun rims. Maybe Sun 17. I wasn't quite accurate. The cracks formed around the spoke holes. The rims did not have eyelets. I was new to the touring world, and the Internet wasn't what it was like today, so I didn't know everything I should look for. Have only broken two spokes since then, and that was during my 2000 Spain tour.

Thanks for all the help, guys!
I'll keep all your suggestions handy.

For now however, I'm gonna stick with the rear panniers for some short weekend tours that don't require crazy loads, and once I start doing longer ones, I'll add in front rack and panniers.
The Arkel ones seem like a good fit.

I just went to fit my LHT (62). It's a beauty, but felt like a was stretching a bit to get to the handlebar (no bend in elbow).
Asked them to put on shorter stem and one more height spacer, I hope that will solve for it. It'll probably be done by next week.

Almost ready to start touring! Very excited

That's a common problem with LHTs. The top tube on that bike is too long for a Lot of people. If you don't have short reach handlebars, I'd put some of those on it too. You can generally find them pretty cheaply. You might even find some nice ones for really cheap on CL.

After I had posted I ringed up another store I didnt know about. They had a size 58 DT in stock. Tested it and felt 100x better. Ordered LHT in size 58 right away. Much more confortable reaching the handlebar, sitting position is easier, little bit more straight up.