Well unless you over do it, strapping the forks down isn't an issue.
My first chopper spent more time strapped down for the first couple of years than most people would believe.
It got strapped down EVERY NIGHT unless I was on an overnight road trip!
Why would you do that you might ask?
When I bought my first chopper I was living in an apartment that I wasn't comfortable leaving the bike outside all the time when I wasn't there, paranoia maybe.
So -- I went and bought an F150 pickup, ramps and proceeded to build a 6FT tall in the back cab over top the bed of the pickup truck.
Installed a chock in the front, mount spots to store the ramps etc.
I would drive the bive up the 10ft long ramps and park it in the pickup truck -- It got strapped down all the time so I could both move the truck and more importantly so I could close the door to the custom cap (98"bed, 99+" bike!).
I still stand by my opinion that the straps should all work towards the same goal (down and forward into chock). I have seen videos showing both ways and I have even transported both ways myself, but have since gone to down adn forward after too much trailering to suit my taste (never would be my choice - although I did have to trailer my first Big Dog home when I bought it -- couldn't get anyone else to ride 3hrs to go pick it up and I wasn't willing to wait).
Whatever method you use, just make sure their tight and stay tight!