I had to adjust the hooks on the rear panniers so the back one was in the middle of the bag, to get the bag set back far enough to clear my size 13 feet.
When I laid out my gear and started packing my bags, I started with the heavy stuff in the front bags, and kept packing until they were full. With the sleeping pad under the seat, the food in the trunk bag, all I had left to put in the back panniers was clothes. That took up about half of one back pannier bag. I added a little more food, putting it in the back right pannier. Oh, then I added an extra stove (sterno backup), an extra pair of shoes, another shirt... basically I added just because I had space available.
So, yes. I could have done my tour with just the front bags, trunk bag, and a handlebar bag. Of course, it depends on what you like to bring. I'm in the Navy and have been trained on redundancy for 18+ years. So, I think I overdid it with the gear. Not a lot, just a little. A little trimming back, and a handlebar bag, and I could have done it without the back panniers.
Also depends on what radio you're bringing
