I hate to say it at this point, but that configuration is a very bad idea as those shoulder belts have no side restraint, and could easily slip off in an accident. I know it may feel like they're on good and tight, but trust me I've seen too many people seriously injured by doing the same thing over the years. I strongly recommend that you either get some proper seats sorted ASAP, or go back to the standard belts until you do. Using that setup as it is could result in some very serious injuries to yourself, and nobody wants to see that matey.