If you don't get the visa in advance, you run a small risk of immigration asking to see your return ticket and denying you since technically you are required to prove you are exiting the country before your visa exempt period is finished.

The consulates and immigration people won't accept an itinerary without an actual confirmed ticket number, which you only get after paying for the ticket. Before you pay for the ticket, all you can get is the 6 digit booking reference number that all airlines issue which is NOT an actual ticket number. So a "on hold" itinerary won't qualify for a visa. Your best option is to buy a full fare fully refundable ticket on a major airline then canceling the ticket to get a full refund.