I agree that phase and frequency and LF filters can help but are not a complete substitute for sub placement. Your advantage is the latitude to place a bit away from the walls. Get the largest sub you can. I have owned undersized subs; it is not great. I would advise to work fast to get through issues. Sometimes people get lucky but the trial period ends quickly. Good luck.
Subwoofer Advice & Therapy :)
Presently I have it narrowed down between three subwoofers - JL Audio E 100, REL T/9x and the Arendal 1723 1S.
Yes, there are tradeoffs in regards to the connection - high vs low. Also a bit of difference with dimensions, subwoofer size and a marginal price difference. My setup - First Watt F8, Modwright LS100 preamp, Zu DW 6 Supremes, Schitt YGGdrassil + LIM DAC, Modwright 9.0 tube phono stage and a Clearaudio Concept black with the AT Art -9Xi MC. I am leaning towards the Arendal, as it has a 60 day audition period, a visual app for set up and has 13.8" sub vs the 10" on the REL and JL Audio.
The other tradeoffs I know exist are in regards to the position of the sub and the size of my listening room. I only have one front corner location (with some room between the back and side wall). This is a large room with 12 ft. ceilings thats approximately 28 ft by 24 ft. In a perfect world I would go the next size up for the sub or go with two but the other trade off is the wife, who would not buy into the size or placement elsewhere. Note I am not up to trading in the wife at this time after 40 plus years 
I would appreciate your thoughts on these subwoofers with my existing layout and system. Mainly listen to jazz and R&B. Not looking for a booming bass but would like to hear a bit more especially when I listen to some classic rock or Indie. Thanks in advance..........