Sorry, I can't offer any useful suggestions either. I have a TX 250 and I use the Vertex tarp with it usually, or sometimes I use the smaller "XL" tarp that came with it.
With a radical sense of hope, I strive for the seemingly impossible.
Could always look at one of the ENO tarps. Hey are relatively inexpensive and have been just the right size for me this past year. I have an NX 250 coming tomorrow and I can't wait!
"May God be with you and may the Devil be crushed underfoot as you march for peace on the skulls of our enemies, for goodwill, security, and a quality of life that comes only with Democracy" -Ted Nugent
I have an NX-250 with the Vertex tarp and almost always set it up in porch mode, I never camp in a state or provincial camp ground only on public wilderness land. I have never had a problem setting up the tarp as I carry a small saw with me, believe it or not in this day and age of leave no trace its ok to prune growth back, it doesn't harm the tree or bush if you remove some of the small branches that my be in your way. The smaller branches also make an excellent tension system when tying out your porch.