My 29 has held up well on rough roads, our paved roads are not much better (as you know) but on back roads at least you can take it slow. The drive you mentioned is a lot of rough road. If quality is desired and price secondary, Northwood makes a TH called Desert Fox that might take it. Its chassis is rated "off road" and it has a very high cargo capacity not to mention it is true 4 season. The 21SW is something I could live with.... check it out.
Northwood | Desert Fox 21SW
On I-65 S to I-85 N through Montgomery Al, I experienced the roughest road of my life. The bouncing rubbed through a strap and the bike fell over; other than that, the structure ... even moldings, etc. did well. I did install EZ flex before the trip and maybe that helped some. If you add these, PM me I have a tip for you.