I don't really adjust the length of the lanyard on my ascenders much. Most of the time I just use a girthed shoulder runner, which is close enough for me. However, lately I've been using a purcell prussik which I find to be more streamlined than other adjustable lanyards that incorporate a loop or tail. Though this is only helpful if the ascender has a dedicated lanyard and other climbers are going to be using your ascender as well and will want to adjust it to their preferred lenght.
If you are jugging on a line that is seperate from your climbing line, like a static, you could just use your flip line lanyard as well, if you didn't want to carry anything extra other than the ascender. Just move it off the D-ring and onto the bridge or central tie in on your harness. I guess this also assumes you use a rope and hitch (or microcender) combo with carabiner attachments. Jug the line, install climbing line, reposition flip line lanyard. Heck, leave the ascender on the line if you've got the access line tied off at the base.