Should I add guyouts to my Solomid XL?

I think Ron Bell has been asked and answered this question before. You could email him directly.

There was a very technical study of wind dynamics and force on tent pegs on BPL years ago. My dim recollection of my take away was that one should “double guy” to the ground at opposite angles each attachment point to spread the transferred load. The attachment point is the top of the triangle, the guys are the two sides of the triangle, with the ground being the base.

You are dealing with a SOLO tent here, similar to my TT Moment DW so two guys should be enough for such a relatively small amount of fabric area. Much like your diagram my tent has 4 guys in generally the same locations as yours, all factory installed

2 main pole sleeve guy points (one at each side of the tent)

2 end guys halfway from each end (3′ sticks or hiking poles to be used here W/clove hitch around the poles and the guy line continuing down to its own stake.)

I’ve found that by adding 4 fly hem stake loops (2 on each side) my fly barely flaps in high wind gusts (50 mph or above). This was a revelation to me and I feel most backpacking tents should have them as standard equipment. Tarptent has evolved their flys to have hems much closer to the ground than many tent makers, which I appreciate. They still vent very well in humid conditions.

TIP: I carry pre-prepared color coded guy lines with small Delrin hook at tent end and sliding Line Loc tensioners on stake end. This means that if a sudden, windy storm comes up at night I can quickly attach the guys. Usually I know the forecast and if there’s any question I put the end guys, poles and stakes up B/C they take the longest to set up.