Here is the complete two-line gas tank strapped to the tray. The green bands are
Velcro plant ties from Lee Valley Tools - a steal at $3.80 for a 30' roll.
A loop at the back for the vent line.
The tank tray bolts with their two washers were hard to put in place with the tank in the way. Here's a way around it: grab the bolt and washers with a magnetic pickup tool...
... and put the bolt in the hole.
Once the bolt is in place, slide the pickup tool off the bolt.