You'll have to use a mod for it, there are plenty in the workshop. Locate one, find the modID in the description or URL, then add it to your hosting.cfg file, using the line steam_ugc=modID,modID etc

The only way that is known at the time of me typing this is to make an item/items -1 or lower, the total weight is 41Kg instead 40kg with -1kg (next to mass -1) you can use big numbers if you wish to but using these numbers will make the item float when dropped but if you leave the area and come back you can pick it up again.

Now there is a command you put in the hosting.cfg file
g_playerWeightLimit=100
changes it from 40kg to 100kg