Some things that are likely to break when you go down:
1. Windscreen - take it off
2. Front blinkers - buy a set of rear mounts and swap them out (you have to drill out the hole on the stem a bit, easy) or remove them while your off-road
3. Side mirrors - remove them (at the last Roaming rally the trail I must have ran across have a dozen broken mirrors)
4. Handguards - get a set of bark busters
When it comes to weight there is not much that you can really do other than bring minimal gear. I guess the biggest weight savings I can think of is to swap out the stock exhaust...maybe throw in a lithium battery. That might knock off 15 pounds.
As for protection:
1. Upgraded skid plate (despite having the well made BMW upgrade on my current GSA, I still have a ding in my exhaust cross pipe from gravel)
2. Cylinder guards (the OEM are good, but my Adventure design extensions have saved my ass several times)
3. Headlight guard
4. TPS guard
5. Snorkel ? (One of those things that you don't know if you'll need it until it's too late...it's an easy mod. I have a post of my system on a thread around here somewhere)
1. I've found the air temperature mod devices useful for slow technical maneuvering. Low speed throttling is smoother.
2. Steering damper (didn't know what I was missing until I picked up a brand new hyperpro here for $150)
3. Tires - the TKC has been the go to tire for most GS riders off road, but the Mitas E-09/dakar is a much better tire for the riding it sounds like you are going to be doing. I just got my first set this summer...wish I had them for the Roaming Rally in June...they are true dirt tires and since you are trailering up...that's the way to go in my opinion.
1. I always use MX boots when I'm taking my bike for relatively serious off roading. I think Ankle support/protection is critical when you are riding a moto off road...particularly a big heavy bike. Also helps when you're standing on the pegs all day.
2. Ditch the knee pads in your pants and get MX style knee protection, I have a set of Thor something or another and they are much more comfortable and protective.
3. Knuckle protection. I don't use the MX style gloves, they are light weight and airy, but they don't offer enough protection. My Rev'it dirt gloves, have plenty of scratches on the knuckle guard to prove their point.
4. I actually don't have one, but a compression suit/roost guard etc. probably offers the best protection if you are riding exclusively off road.
5. MX goggles (if you have an MX/DS helmet). They let more air into your helmet and tear-offs make them easier to keep clean.
6. hydration pack. Amen staying as cool and hydrated as possible is critical. Forget the in the jacket crap and go with a backpack.
Above what you need normally, so things that I have found to be useful and don't take up much space or add weight:
1. JB Weld
2. bailing wire
3. Duck tape (they make it in black)
4. 18" inner tube? Rumor is it will get you out of a pinch and works with both rims, but I have thread on this an no one every confirmed it, I've personally usually carry two tubes, but they are bulky. The rear wheel of the BMW spoked rim has an off set valve stem, but I have confirmed that the last tube I used (for thousands of miles) was a centered stem tube. If you dent a rim or rip a tire, your plug kit will be useless...it's happened to me twice and it happened to at least one at Roaming Rally in June.
Just thinking out load here...