I have to laughbecause I did the same thing. I use rubber wheel chocks, slide out and stepsupports and I make sure my corners are stiff. I get very little movement and most that I had was stopped with the slide out and step supports.
I found the extended size on ebay after posting this. I never knew there were two sizes!! Unfortuantely, they are twice the cost ($70 each). So I guess I will look into making my own or stick with the standard under the wheel chocks for now.
Can someone tell me the spacing between the tires on the new Zinger TT ? I am hoping my BAL X wheel Chocks I have now will fit. If not, I will order the BAL Extended Fit X Chocks for the new Zinger TTI will be buying this fall.