you do input validation I assume.. (you do don’t you) then it is just add another validation i.e.
if (input_truckload) >= 50 then return (‘Invalid Input Truckoad is greater than maximum for one order’)
You have entered as %input_truckload% instead of Each are you sure that it is Truckloads of product and not Quanity Each of this item (y/n)
(default entry is n (no)
or simply remove the truckload field entirely and instruct salesmen that 1 truckload is ‘x’ quantity of items and dynamically change the ea to truckloads for the shipping department