I start by trying weight in the back. That's where it helped most for my outboard but that was a tri-hull so planing was not a big issue.
As far as taking it out when finished, it just depends on how much more load your trailer and trailer tires can carry and if the added weight pushes you over your tow limit. On my boat it wasn't neccessary as I was well below load capacity. The only reason I pulled the weights was so they wouldn't rust and I did that after I got home..