How do you do the rear without taking off the pipes on an interstate? Do I need a 2nd jack?Hi Oss...
If you already have gone for taking your bags off, you're a bunch of the way there. I take the wheel off
"the Daniel Meyer way"... sort of... anywho... besides the bags, I also take off my rear fender
section. And I remove both shocks so I can sink the bike down a little and get the axle out...

It is important (I think) to jack the bike to where there's no tension or compression
on the shocks - the rear wheel is barely touching the ground - before you remove
the shock bolts.
It is important that you have good control the speed of your jack when lowering
your bike because you wouldn't want it to come down like a sack of concrete
with the shocks off.
There might be stuff with an Interstate's top case that make taking the rear
fender section off hard to do, Ida know. If you don't take the rear fender
section off, then you have to jack your bike high enough to get the wheel out.
Some kind of thing to replace the shock (maybe even the shock, I never tried)
will be needed after you get the axle out and then need to jack the bike up
with no shocks on it. I use a big turnbuckle...

It is so easy to get to stuff down there with the bags and rear fender section off...

I mostly differ from "the Daniel Meyer way" in that I man-handle the
wheel and final drive less than he does. The last time I had my wheel
off, I got it back on by having the bike jacked up just the right amount
that I could push/roll the wheel/final drive back into place while the
ground (not me :-) ) was holding the weight of the wheel.
Good luck!
-Mike