Yes, you can drink wine and beer inside a party bus, but you will need to consider a few things before you make it a point to invite your guests for a party.
First and foremost, you will need to make sure that your guests are the drinking type, which means they are highly capable of drinking the amount of drinks that you are going to serve inside a bus. Of course, there are always some people who will not drink, so it is absolutely necessary for you to respect their decision not to. Do not force someone to drink if he or she is a non-drinker. You are simply endangering his or her overall health if you a force a drink on his or her mouth.
It may be necessary for you to limit the amount of drinks that you will serve inside the bus so you are ensured that your guests will be able to get home as safe as possible even when drunk.