A few thoughts IMHO:
1) Unless you hit rain, you really don't need to lube the chain on a 1200 mile trip. While it would be ideal, it will not kill your chain if you oil before you leave and then when you get back.
2) WD40 will not kill a chain and will not eat o-rings. There is proof all over the place of people using WD40 only for chain lube for well over 30k without issue. I have used WD40 on trips, works fine, in fact I just did a 1500 mile trip on my KLX250 dual sport from NY to WV, all sorts of rain, mud, dirt and muck, used WD40 after each wet day without any problem at all.
3) Aerostich sells small squirt bottles of the Dupont Teflon lube if you really want peace of mind, it is expensive relative to a small can of WD40, but available if you must have it.