Glad to hear that you like my boom tent. Here is another photo.
I had it custom made to my drawing by http://www.sailorstailor.com/
It is 8' long, and wider at the front [82"] than the rear [72"], with the rear width dictated by my running backstays [were it not for them, I would have made it wide enough to reach the side edges of the bimini at the back]. Sorry but it has been a few years, and I don't recall the price. What I did to determine the size needed was mock up a cover using a bedsheet, and then measure the result. I can tell you that it is made from 2 pieces of fabric [white polyester "army duck" - not normally one of their available colors, but it was left over from somebody's cancelled order], with a longitudinal center seam that is very strong and stretch resistant, with a grommet at each end. It is not actually supported by the sail, it is stretched taught between a bungee around the mast and one around the topping lift eye at the end of the boom. There are also grommets at the mid-point of each side which are fitted with tiny carabiners that snap onto the lifelines. The front corners dip under the lifelines and are hooked to the shrouds with tiny bungees, while the rear corners are bungeed over the top of the bimini to its frame [visible in above photo]. A nice thing about this is that after fitting the boom tent, the forward bimini straps are redundant, so if you have a slip like ours with a finger pier, you can wrap that strap around the bimini frame to keep it out of the way, making boarding/disembarking much easier. The tent not only provides shade and sheds rain, but it does a great job of catching a breeze and directing it across the companionway & cockpit.
Now having both it and our blue bimini, I'd have to say that if you are going to have a boom tent made, go with a color as close to white as you can find. The temperature difference underneath is significant. Here's one more photo, which illustrates that with the boom tent rigged, the mainsheet also becomes redundant - in terms of keeping the boom centered over the boat. Much easier to access the cabin with it out of the way.
I'm glad to hear that you have a new trailer on the way. I've gotten ours adjusted so our
sits lower than the way they had set it up at Dave's, and now that it isn't supporting the boat, there is some further adjustment that can be made get to the front rollers even lower. It was great being able to just roll the boat back & forth by a foot to paint the entire bottom.