adjusting downstops without droop gauge
 

I do not have a droop gauge to measure downstop settings

are there any other good ways to do this?

you can set the droop using your ride hieght guage but first take the wheels off and put the car on a flat surface[ table,setupboard ] to make sure chassis is straight and flat, then using r/h guage adjust distance betweentable and bottom of hubbs from one side of car to the other. once this is done put the wheels on and set your ride height. then using your guage starting at one end at centre of chassis lift car up to the point where both wheels are just touching the table (make sure both wheels lift off table together) measure it there and the difference r/h and this measurement will give you a good starting point from where you can set it to where it works best for you . same method for the front but take bumper off to easily measure from front of chassis.i've used this method but its a little bit more acurate with d guage, once you first set front and back up if you need to adjust droop you can do this making sure you make equal adjustments from left to right (1/4 turn left and right saves removing bumper all the time :D
hope this helps you out a bit :)