As an investor, having a license is very helpful. However, if you choose not to get one, it is perfectly fine. When wholesaling you just need to make sure that your contract is completely valid in the state you are operating in. Have you attorney look over the contract you're using.
In my agreements I always give myself the ability to assign my contracts. Even if I am using a contract drafted by the sellers attorney, I will add an addendum which gives me the ability to assign.
I explain to the seller that there are times my partners would like to buy me out of the deal or I will be creating a new entity to hold the property in so, I need the ability to assign my agreement to another entity. As long as I explain to the seller that they still get their agreed purchase price, I have never had one that said no to me (adding an assignment clause).
Also understand when you wholesale, it means your buyer is another investor. NOT the end consumer. So your buyer-investor knows exactly what you're doing. You do not have to double close necessarily. Once I assign my contract, I create an invoice and send it to the title company handling the closing and I get added on the HUD-1 on the seller's side as an additional payee. If my seller asks, I explain to them that my partner is buying me out of the deal as I have informed them before; which have never really happened to me because my sellers are just happy to receive the money that I promised them and for them to be rid of an ugly house.