We also installed a 15V dc-dc convertor to supply the oven with 15v.
It works well enough. You need to have patience when it heats up as it can easily take 25 minutes to get fully heated. The lowest rack is a bit too close to the bottom of the oven, and in turn the heating element, so things can burn easily on that lower rack. For what it is, we are generally happy with it. We have made bread, chicken, and vegetables in it. Thinking some type of pizza stone might help, but have not tried one yet.
For the price, and ease of installation, it was the right choice for us. Having any sort of oven is a big win as we live and travel with our rig full time. No question that a proper marine propane oven would be better, but at $1000, we will work with this one.
My wife will post a blog about it one of these weeks and I will put the link here as well.