Is Texas really a place for this kind of trip?+
It is, if you go west of the cities. The state is mostly known for its urban sprawl, but the Hill Country has had river retreats and quiet ranches for decades, and the Big Bend region is one of the emptiest places in the country. What you will not find is a dense cluster of options the way Sedona or Big Sur has. You pick a landscape first and then see what is in it.
How remote is Big Bend, practically speaking?+
Very. The nearest commercial airports are four to five hours away by road, the last town before the park is small, and inside the park there is no mobile coverage across large areas. Distances between fuel stops run over a hundred miles. Treat it like a small expedition: full tank, spare water, offline maps and someone who knows your dates.
Can I come in summer if that is my only window?+
In the Hill Country yes, with adjustments: everything outdoors happens before nine in the morning or after seven in the evening, and the middle of the day is for shade and cold rivers, which is exactly what the locals do. In Big Bend, summer is genuinely risky and most people should not plan walking there in July or August.