Subwoofer

i think the dual driver helps with room nodes and if you only use one subwoofy

KEF dual driver subwoofy gets good reviews

https://international.kef.com/products/kc62-subwoofer

I think this SVS is in my future

https://www.svsound.com/products/3000-micro-subwoofer

The issues with no choice in placement is dealing with room integration. Any subwoofer which is big enough will do IF you have the appropriate measurement and EQ gear.

Personally a huge fan of HSU but I use mine with a miniDSP or the room correction built into my HT receiver. 

What’s your budget, and any size limits/restrictions?

I don’t think one subwoofer is a good idea, in general, in addition to speakers with reasonable base. Two can enhance and enrich the sound. One will just muddle it while it will sure add the thump, which I will need for 3 minutes a day.

(and I wish it weren't the case, I tried for almost a year now with different (single) subwoofers)

I think grislybutter is right...

I bought a subwoofer years ago because my MIssion Cyrus never go down 45 hertz really...

With an organ music album it is a pity...

But the sub alone dont cure the problem and worsened it because the unbalance it created...I sold it on the spot... :)

I think it takes more than one sub  to balance the system and the room...

 Sadly at first but fortunately at last , my headphone replaced my dedicated room now because i sold my house... My headphone go so low under 30 hertz that i feel the wave with my body and feet by bones resonance and it is like the owgan was in my room... No sub is needed...And my new headphone beat my past speakers in their well tuned room..