With the FEC you can open doors,without much heat loss,so trying a 1/2 pan of spears is good.
Check any cookbook for approximate cooktime,and do a trial run with several pieces.You can bracket,with your cook temp,quickly.
Fresh,trimmed/broken stalk asparagus can almost be eaten uncooked-so it isn't a long trip.
If you are grilling,that answers the question-pick up one and try it.
Ribdog may be closer to his notes,than I am to mine.I apologize for not keeping every small vegetable in memory-but the other 97% of product that actually benefit from the smoker usage seems to clog my memory.
As we cook more,we find that not everything lends itself to a "smoker"/slow and low cooking.
Yes,we want to "prove" we can smoke anything,i.e. the baby's formula,the dogs kibble,the teenagers popsicle,the brides raw veggies,the grandparents' poached eggs.
Many items are far better to play off of a major smoked entree,and allowed to stand on their own quick cooked/grilled flavors.
Just a thought,but quick cooked,fresh spears do seem to go well along side many meats.
Just don't eat them ,before the guests arrive.