Crossing borders over land versus air is always interesting. I have only done it a few times (USA to Mexico/Canada, Romania to Bulgaria, Bosnia to Croatia, to name a few.) After the Bolivian salt flats tour was done, we were dropped off at the Bolivian/Chilean border in the midst of a wind storm.
The process went as follows: wait in line and try not to get blown away until you are called inside. Pay 15 Boliviano per person to get an exit stamp. Locate your driver and put your bags in the van. Take a photo of the sign that divides the country. Board the bus for the 45 minute drive to San Pedro. Arrive in San Pedro and go through customs. Get dropped off. Walk to Plaza de Armas and find the Portal Andino Lodge. Purchase a ticket for 12,000 pesos ($19) to the airport which is an hour and a half away. Locate the St. Peter restaurant. Order a llama burger and llama empanada along with craft beers. Eat and drink. Pay the $34 tab. Realize that you just spent $34 on a llama lunch. Question your budgeting and decision making. Wait for bus to airport. Get on bus. Get out of San Pedro.