Yep, no way around things (practicality wise, that is), other than radical "EQ'ing", speaker and seating placment changes (still have challenges thereafter), or, yep, massive bass traps/resonators, etc. Your most pracctical is to move speakers/seats, or (from what you're stating), using some Parametric EQ'ing for your system. At the price of your best option is to "EQ" the sub (fix the 40hz spot), and make sure it's not in the 80hz "hole at the 1/4 points of the room. Basically, you need to place the sub in the "middle" of the room to rid the 40hz peak from the sub/room interaction, which might not be practical. Otherwise, place it in the middle of the front wall behind your center speaker to help minimize the 40hz peak(by putting it in the null there!). Also, sitting in the middle of the room, side to side, will lessen that 40hz mode. Still, 80hz will be peaking there, but you can work that somewhat with crossover/rolloff of sub at 80hz, as well as coupling with Logans rolled off at 80hz a bit, if not perfect, but workable. (and you should be rolling the logans off at 80hz!!!!("small" on the pre/pro, yes!). Running em full range has set backs, espeically in that small room, not to mention dynamic range limitations.(Use THX guidelines).
Best bet is still to add some Parametric EQ to at least the sub ideally(but workable otherwise, as well as check level of sub balance vs. system), and get sub out of corner, and into middle of room more!.
You indeed should do bass traps in teh corners to help remove the sting there, and help room sound. Also, you might be doign a bit too much absorbtion. Try pannels on the sides, a few maybe upfront(although Logans don't like absorbtion behind their speakers so much, so beware!). Really, that small rooms needs some more "diffusion"! Particularly since the Logans severely limit off axis reflections greatly, by their phaae canceling dipolar design! I've sold Logans for years.
Basically, your problems can be tamed GREATLY, by moving the sub into the middle distance/dimmension (if not middle of the room more), adjusting levels/crossover, tweaking, speaker and seating placment (moving speakers near 1/4 points would help 80hz peak (how high is ceiling though?), and/or sitting closer to 1/4 point between/from the front/back wall), and fidgiting with set up. OTher than that, EQing should be considered.
For the record, the Rives Parc is the most transparent Parametric Analog device you'll find for doing speakers, but you'll pay a lot to do all of them with your system price range!...otherwise, concentrate on the sub/levels/eeating...you have no other options really