Usually Fly Southwest with my wife who is on a Companion Pass (already qualified through 2013) using Chase card. I was thinking that on long flights that are traditionally full I could use points or price to buy the third seat between us. So for 1.5 times the points cost per ticket we could be assured of no one in the middle with plenty of room to ourselves. Some wanna get away points are low enough that its still WAY below business select, etc. Any problems doing this? I assume as a POS booking you also get pre-boarding which would save an early bird boarding cost too....
FYI I am not a POS - but does that really matter? Is there a "technical" requirement?

Also - woudn't that also allow me a refund on flights that are not oversold per their POS policy? Would it be discrimintory to deny me the right to buy a POS ticket if I can fit in one seat?