My light touring setup is all Revelate bags and harnesses. It really limits the amount you can carry vs. panniers (not necessarily a bad thing), which is why most bikepackers need to add a backpack for water and food. You will probably not notice any significant difference in handling adding some weight to the handlebars and a frame bag. However, make a list of everything you want to bring, and you'll find yourself running out of space pretty quickly, and having to add more carrying capacity.

I don't tend to weigh the load, because there are so many variables (water and food being the main one). However, as a rough estimation, I'd say 20-30, 30-40 and 40-50+ pounds respectively.

Like cycomute said if you have a long unbroken distance of road riding it might be worth starting off with road tires then switching when you get to a long stretch of dirt. Again this is something you can play with before the trip so you know how the bike handles on the road and dirt under load. Just because a bike comes with one set of tires doesn't mean they're optimum for your use. Also you may get the on/off road versatility you want just by switching one tire.

Oops, right.

Yeah, for backpacking the weight of consumables vary tremendously according to remoteness and length of stay. For bikepacking on roads, I suppose it will be much less of an issue.

Not necessarily. This is the age of Helmart and that means the distance between supply points is often quite large even in "civilized" areas. For example, there are very few places to get food along the Missouri River on the Lewis and Clark ACA route. If you follow their route from Sioux City, IA to St Charles, MO (576 miles), there really are only 3 supply points...Council Bluffs, IA, Atchison,KS and Jefferson City, MO. I found that I had to carry 3 days or more of food or I would have to go 20 to 30 miles off-route.

If you are going to follow the TransAm, I'll guarantee that you won't find much from Girard, KS to Pueblo, CO. You won't find anything from Alexander, KS through Eads, CO to Ordway. There's not even much in the way of people out there. I grew up in that area. In fact, I'd suggest following US50 through Lamar, La Junta and on to Pueblo for that part of the TransAm. It's a lot more interesting and you aren't the only thing around for miles and miles.

Sometimes I feel like Greta Garbo, though! LOL

Exactly why I have been posting questions here, so I can get help! I can do a fair Ringo imitation if necessary... LOL

My wife got me the Axiom Typhoon 45 liter (combined volume) panniers for Christmas; no problem with heel clearance. I think someone asked about attaching a tail light to the rack: this one works great for me after using some locktite: https://www.amazon.com/gp/product/B01...ilpage_o05_s00.

I bought a very small saddle bag (https://www.amazon.com/gp/product/B00...ilpage_o00_s01) for tools, and a small handlebar bag (https://www.amazon.com/gp/product/B00...ilpage_o08_s00) for electronics (unfortunately, too small for my iPad Mini, though). I'm thinking of buying a pair of Cleveland Mountaineering Everything Bags (Cleaveland Mountaineering: Everything Bags) to mount on the front fork in order to hold a few things, like a rain jacket, and a couple of liters of water when I eventually reach the desert. With the ease of strapping my tent, bag, and pad to the Jones Loop handlebar, I feel like I will be set for storage...though I have been considering a Revelate Design Tangle bag to use as a feed bag or maybe for a water pouch (my dromedary bag would be too big, but I think that one of my Platypus bags would work). I'm afraid, though, that the tangle bag would mean losing both internal frame mounts--one of which has my whimsical "bird cage" (Amazon.com : Portland Design Works The Bird Cage Water Bottle Cage, Black : Bike Water Bottle Cages : Sports & Outdoors) and the other will hold, when it arrives, my Ti mini u-lock (https://www.amazon.com/dp/B0155L1G9W/...I2WFLWIGRH5P6H).

Oh yeah, for those who keep telling me that I'm putting the cart before the horse, I've been riding up and down the local hills almost every day. (My neighborhood is built on the Indiana dunes.) My cadence is still too slow; I hope to focus on it after I pick up the Garmin Edge 25 Plus Cadence Bundle. (I cannot afford everything at once...or at least I don't want my wife to see packages arriving every day!)