I had one, I feel sorry for you, look at a Yamaha WR with motard wheels, about the same except 70 mph on hyway and way better offroad.
I bought the Panniers and rack as well as the skidplate from Happy Trails in Idaho. Got 10k miles on the bike and it really is a blast. I live in the Mojave and the sand is loose and deep. No problem for this crazy little bike. As for 2-up riding, you can still do it with the bags, but prob only around town. Not enough power to do more than 55 with 2 people. I can hit 70mph no problem on the desert roads, but its wound all the way out. I've beat this thing and it keeps coming back for more. Sure its not fast, but as far as fun bikes go, its got it all.