i hope your trip goes well. First, give yourself some extra time because navigating the airport in a mobile device can be a challenge. Second, if possible, I recommend an early morning flight. Usually the airport is a little quieter, but it is up to you on the timing of the flight. Next, upon arriving at the gate, please tell the gate agent, that you would like to pre-board. Let them know the level of disability, that is, is there any mobility? Standing? Transferring? Then, preboards are called to board first. an attendant helps speed the process along by getting the person on board and arranging to gate check the wheelchair. Or if assistance is needed for more assistance, the airlines have a special wheelchair that can get on and down the aisles. It is not ideal but it can work.
If if you go the frequently asked questions in the Southwest.com website, you can find more information. Safe travels.