My thoughts... Firstly I'd suggest a minimum of 3 endurance sessions a week improve, I guess 4/5 would be better. I'd do weights twice per week kept simply squat/push/pull. Squat, bench, dead one session - power clean, press, squat on the other. I would need to do twice per week as a natural rake build, whenever I've tried once per week what little strength I have falls off a cliff especially on squats, not so much on deads and presses somewhere between. If you can get away with once per week maintenance try squat, bench, dead (alternated weekly with PC), press assistance. The less time spent training strength, the more time you have to build endurance.
If you're maintaining strength you don't require the same volume or frequency, but must maintain intensity. Apparently you can do 1/3 of either and maintain, I find I need more frequency than that, as above. 5x5 squats won't be conducive to redeveloping endurance and is unnecessary. If you've been doing 4x5 for instance, just do 2x5 with the same weight... and so on.
Sack the circuits / WODS. I don't see the point given your aims, they just eat into your recovery ability.
I don't think developing endurance is too difficult, just put the time in at appropriate intensity. Focus on long-steady duration, more intense if you are training for less duration over the week (threshold type stuff) and save intervals (hard ones anyway) for short spells to peak the base of endurance you've establishing leading up to that point.