You should be ok with DVD+R as its been around longer as a format most standalone players don't have a problem with it.
DVD+R DL is a much newer format hence why we recommend changing the book type to improve compatibility with standalone players. I don't know your drive or if firmware is available to allow you to change book type - I assume you have tried Google ?
Lightning UK!, the programs author might be able to tell you if any of the tabs with the book type option on ImgBurn are suitable for your drive, I think you can also change book type on compatible drives with DVDinfoPro, you might want to try that.
Lastly, use ImgBurn to check for firmware for your drive, with ImgBurn open, right click on the box that displays your drive and then select Firmware Updates from the list, this will take you to www.rpc1.org and a list of available firmware updates, if your lucky there may be a modified firmware that allows booktype setting.