The TTB can be pretty capable off-road. They're pretty stout and you can pull some pretty decent travel with them. They may be a pain to work on, but they'll get you through a lot. Hell, I wheel my truck with the d35 SLA and do alright. Lol.
Solid axle isn't the end all be all, but it is a good platform. A built Dana 30 would be good up to 35" tires. Any more than that and I'd be afraid to beat on it. The 44 is a much stronger option. But, like you said, can be harder to find. Early Broncos and jeep wagoneers are popular donors because they have a narrowed trac width (wider than a ranger, but narrower than a full size) member "02fx4Red" went this route. You could also go with full width axles. Member "sole" has full widths under his truck. I believe he's running a d60 front and a sterling rear.
With enough fabrication, anything can be made to fit under the truck. It really depends on what you want to do with the truck, what's available, and what your budget is.
2002 Ford Ranger XLT 4x4, ext. cab, 4.0L v6
1995 Ford Ranger STX 4x4 ext. cab 4.0l v6 SOLD