Are you looking to build a single motor DIY electric skateboard? There are many benefits to go the DIY route the main opinions are the ability to change out parts if parts become damaged. To learn how to build an electric skateboard. To get more bang for your buck.
You can easily build a single motor electric skateboard to go about 20-25mph and climb 20-25% inclines. However, longer uphill distances are better off with dual motor and/or if your rider weight is more a dual motor most definitely helps.