I have one of those soft-sided coolers, with a telescoping handle and medium-diameter wheels. This fits my 4x5 camera stuff and I put used film holders in the front pocket.
All I can do right now is post the link for this bag.I got this for my 14x17 and I have a cart that I have to extend the axle and get bigger tires. I do like to get off trail so this will go on my back at some point.
Just yesterday, I admitted to myself that I'm not as young as I used to be and decided to get one of the baby joggers. Did my research and found that most are priced much higher than I wanted to spend. So, I found the cheapest one possible at Target for only $99 (called the Expedition by Baby Trend) and it really looks like it will hold up fine. There also looks to be more space in it than I expected and should easily hold all my gear. I know that the more expensive ones are better built, but for what I'm going to use it for, it looks OK so far. I'm heading out to Joshua Tree this weekend and will give a report on it when I get back.
Jim - if it holds up well, it might be something for you to look into for the 14 x 17.
Dan, after this past weekend in Yosemite I hope I can put skis on the thing! Let me know how it works out. I'll carry the 14x17 if I have to but if I can shoot from the truck or roll it along that will do just fine.
Someone else recently posted their similar rig made from the Calumet large case. He added an axle after riveting some square tubing to the bottom and then added wheels like I did. His case is much more protective and sturdy but mine does do the job well and the suitcase was old, beat up, and free. If I can find his post I'll reference it as he had about 4 photos of the case and how he made it. Maybe he'll chime in here soon and re-post..................................