Tourism visa or business visa?

Hi, I travel to China a few times a year, and have previously been recommended by colleagues in a similar situation to myself to just apply for tourist L types, due to ease of application mainly. In honesty, whilst I usually take a few days to see the sights, my visits are usually more business than tourism related related - I am a sole trader, and my product is produced in China, so typically a visit will be quite short and might involve attending a convention, meeting with business contacts, and sometimes visiting a factory. However, as I'm not part of a big corporation, getting the business M seems like a hassle due to getting letters of invitation, etc. but I also don't want to run afoul. So, what I want to know is... am I taking a risk with the tourist L (particularly if I get it a few times a year over several years), or is this acceptable, and I fit within a grey area? Thanks in advance! Leon