Haney Meadow is a great place lots of options.
Nice Campsite on the Naneum Creek
If your looking for a primitive base camp east of their, I would suggest the northeast corner of the Kittitas Valley, up Coleman Creek Road about 4-7 miles, lots of nice primitive campsites on BLM (no charge camping) and you will have water (needs purification).
Another Alternative is north of Leavenworth and Plain follow the Chiwawa River. Routes through here or east of there will take you to Chelan.
One last option Base out of or near Conconully, lots of nice rides north to the Canadian Border from there.
Wherever you go, have a wonderful time.
PS Should you end up near E'burg let me know, I might try to locate you or meet up at base camp.