Now here is the big question - if your travel will be so rough that you want a suspension fork, do you really think a 700c rear tire that is small enough to fit in your frame with fenders will be adequate on back for your trip?

My expedition bike was sold specifically with a frame that was designed to use a 100mm suspension fork or with the solid fork that came with it. It uses 26 inch wheels. I have used both types of forks on that bike. In the photo, my expedition bike had the solid fork installed. I found that 2.25 inch width (26 inch) tires were good enough for this road without having a suspension fork. It rode a bit rough, but I was really glad I had a heavy duty frame with wide tires. If it was rough enough that I felt that I needed the suspension fork, I really would not have wanted to have a 700c pavement touring machine.

When you said you could use 26 inch wheels, were you trying to ask if a 26 inch suspension fork would work on your 700c frame without messing up the geometry? Interesting question. And if you did that, would that mean a 700c on back and 26 inch up front? I do not know enough about frame geometry to have a clue, so I will not offer an opinion.

If you try a suspension fork, you might want to also order the lower headset bearing race to install on the other fork so you do not have to remove the race from one fork to install on the other. I did that when I bought my suspension fork, when I switch forks I am happy that I do not have to mess with the lower headset race since both forks have the race installed and are ready to swap in and out.