I have tried grangers as well as nikwax.
If your toploader is a relatively new HE smart washer that can sense the load size and only fills up the water partially; then just use regular dosage.
If it is a dumb washer that just fills to same water level then you need to add more.
However, the biggest issue is waterproof stuff tends to float and not really get mixed about in a toploader. And since it's waterproof stuff, it doesn't really get the floating side very well. Especially if your washer has agitate only, and doesn't have a mode that sprays laundry water over the top of the load periodically during the wash cycle. This same problem happens with washing down items; which basically i've given up and just do hand wash.
I would suggest the following. You can handwash, machinewash, or do a hybrid combo for the full deal.
[HANDWASH steps, prewash]
0) hope you have a laundry plastic tub for hand washing; maybe $5 at any store.
1) Prewash just in tub with plain water to get any loose stuff off.
2) add like half a cap to your washing tub with some water, and hand squish it around for a bit, soak is option.
[you can just finish and do the rest by hand wash at this point if you like]
[Toploader MACHINE wash, continue or start here]
3) Dump the tub into washer, add recommended amt of detergent (or subtract some if you added a lot in handwash). Start with regular side out; if you have insulation or comfort layers
***4***) PAUSE the wash after about halfway through the wash cycle. Then open it and squish things around by hand more,
Flip arms and legs so it's now inside out, squish around; this is so that spin cycle gets most of liquid out of insulation or comfort layers; and not trying to spin water through goretex.
5) Let rest of wash program finish
6) dry as recommended. Start drying with comfort layers flipped out, again so it doesn't have to steam through goretex. Use timed dry as heat is needed for activation, and you don't want autodry to switch to wrinkle rid cold air. When comfort layers are dry, flip to the outside, and do a couple minutes for the shell side so it's toasty and activated.
Don't get your hopes up with wash-in DWR, it's only going to do so much.