last minute chuck roast questions

Hey all.  Im still new here.  I have the MES30 and Im about to start my 2nd ever smoke tomorrow morning.  I picked up a nice looking 4lb chuck roast.  My questions are Ive seen different pics on here of them being done directly on the rack and also in a foil type pan.  I dont dont which way to go about it.  I was also going to marinade it with some misquite marinade.  It says to do it atleast 30 minutes prior to cooking.  I was thinking of marinating it overnight.  Is that too long to marinate?  I was thinking to set smoker to 240ish for 4 to 5 hrs and then wrapping in foil and go another 1 to 2 hrs but still not sure if I should do it directly on the rack or to use some sort of a pan  so that it cooks in its own juices?????