If I was buying a rain suit tomorrow, I'd probably get a BMW ProRain3 assuming it actually packs down into the relatively tiny stuff sack they supply with it. You're going to have to put both pieces on regardless, might as well not have a place to leak at the waist... and have it be bright yellow so you're visible. Harley used to sell a rain suit made of Gore-Tex paclite material, I had a Klim off-road rain jacket made out of it and it was fantastic! Super light, packed crazy small, and was absolutely waterproof and dried quickly. Otherwise, I'd stick with a PVC or similar material that can't and won't eventually wet through. In the end I decided to just find pants and jacket that are waterproof to begin with and love my Aerostich AD1's and Klim Traverse jacket.
I decided to just get boots that are waterproof too (Alpinestars Scout Drystar) instead of putting covers over them. The rubber overboots FirstGear sells work great though, and cheap.
I've yet to find waterproof gloves or glove covers I really like other than my winter gloves (warm n' safe classic riders). If its warm I just let my hands get wet so far... but the hand guards keep most of the moisture off anyways.
Dunno if the helmet on the back seat is the helmet you're taking or not, but I'd personally take a full face, or at least something that can have a face shield attached, just to keep the rain, rocks, cow poo, bugs, etc out of my eyes, nose, and mouth. Also helps with wind/exhaust noise.
Sleeping bag, for as long as you're going to be out and the distance you're covering, there's still a good chance of finding cold weather at altitude. Two years ago, in August, a 40* down sleeping bag worked fine except for one chilly night in Colorado. This time around I'm bringing a 20* down bag from Kelty that I ordered from Campmor in New Jersey.
Camping Gear & Outdoor Gear - Outerwear & Outdoor Clothing from Campmor.com
Down filled bags are nice because they pack smaller, but lose all insulation if they get wet. Synthetic bags retain some of their insulating properties when wet and are often less expensive, but typically pack much larger and are heavier. I went with down because for me the ultimate pack size was more important, and I trust the waterproofing on the stuff sack I have it in.
I'd personally find a tent that packs smaller than 30" wide, but since you have it and it works for you roll with it. The Eureka Backcountry2 is a decent size for a solo moto camper... and packs to 15" long. And is $180 or something like that, also from Campmor (only place that sells it).
Do you have a sleeping pad to go between the bag and the ground? Lots of options there... currently have an insulated air pad from Big Agnes, but might revert back to a self inflating mattress like a Thermarest or the REI branded ones to save me from huffing and puffing at night. If not for comfort, pads give insulation between you and the ground keeping you warmer.
I'm leaving for that part of the world on a one way trip in about a week I hope, I might still be out that way God willing when you're rolling through. Don't worry so much about the gear, just get out and ride!