Basic one room design tips? [updated]

Hi, this is my first post here (which I have now made changes to and hopefully made better!) :) I am in the midst of writing and "producing" my own (first) album and am in need of some advice for setting up a very basic but effective room design to do my recording and mixing, with a focus on the latter. My recording is typically a solo effort and involves vocals and acoustic and electric guitar. No live drums. I don't require a lot of space for recording. Isolation is not a concern at this point. I'm looking to equip the room with Mackie HR824's or similar. The room will be built in the basement which currently is an open area. External walls are double insulated with rockwool (we have cold winters!) and are not drywalled. Floor is concrete and ceiling is open floor joists. Usable space dimensions are approx 19'x22'x7'3" (7'3" to the joists, height up to the floor is closer to 8'). Notably there are 3 windows in the full area, 1 support column with beam, an electrical panel (protrudes from wall framing), and 1 plumbing stack. The image leaves out the rest of the basement that is as well open but unusable. I have modest constructions skills and would hope to spend about 80hrs getting the room together. My budget is around $500 but could move towards $1000. I have made 3 designs that I think might work. I'm hoping someone can provide some feedback as to which one might work best. The support beam seems like it might be the hardest to deal with (design 2 seems like it would deal with it the best). The first 2 designs are based on L.W. Sepmeyer #3 ratio (1:1.6:2.33), although not accurately so. The 3rd design is based on Rod Gervais's example layout from his book. My basic understanding is that a recording room should be asymmetrical and mixing rooms should be symmetrical. Are there considerations in this regard to be made when combining both mixing and recording in the room, and does one design deal with both functions better than the other? Also please note that my wall angles are not meant to be well designed. I'm primarily looking for feedback on the general placement of the room as a whole in regards to basement obstacles and the general comparisons in room design. Many Thanks. Graeme