LTL from load boards is so hit and miss. A lot of these brokers do a very poor job finding out correct dimensions. That'll be a big problem for you. Even more so with smaller trucks. I don't know of any LTL specific load boards. I would recommend trying out Internet Truck Stop load board searching "P" loads (partial). If you haven't already get in with the Flint CHR branch but those folks also are sporadic, all over the place, and have a list a mile long of expedited carriers you will always be bidding against. There may be another branch office of CHR that deals with largely LTL but I'be never found them. I think most of the branch offices just deal with LTL as a customer may have a need, which would be rarely. CHR load board is free BTW you just need to be set up with them and have the T# they assign your carrier handy when trying to book loads. And again LTL will be very hit and miss on there as with anywhere else.