No problems here with my grips and they're cheap/easy to replace anyways. And you're not really going to have your bike loaded long enough to worry about your seals. Just my .02Screw Canyon Dancers. They all mess up your grips over time. Just snake the tie down through the bottom of the fork. It's out of the way of the fairings. Grips stay in good shape. You're not compressing the forks, so you can leave it for extended periods like this without worrying about blowing a fork seal.
Might be a pain in the ass without a wheel chock though. But seriously, you should have a Baxley anyway. Makes loading up so much easier.
The cup ones are what I used to use. They'd mush up the end of the kevlar Renthal grips I had, to the point that I was worried about the throttle binding up.If you are blowing seals from compressing the forks, you have the bike way too tight. Ratchet straps are simply more than you need. A good set of cam-lock tie downs is all you need. Just tie them off right at the cam and away you go.
I've never had them mess up a set of grips beyond just moving them a little. Just need to make sure the throttle side didn't get pushed into the throttle housing. Canyon dancer also makes one with a cup at the ends instead of the strap. I've never used it though.
If you have the money and are constantly trailering your bike, a setup like the pitbull system is about the best you can get.