We've had some success using the Latigo harness, but you have to use it "Differently".
Put it on, but don't cinch down the waist strap yet, leave some slack. After that, cinch down the leg straps so the O-ring is centered over her vulva and you can slide a dildo through into the vagina. Once you're done with that tighten the waist strap as much as you need to to tighten things up.
It might be more body-style specific, but we've found that you can have the waist strap hold OK using this method. Then, when you slide the dildo in (loosen the waist strap, pull off the harness, insert the dildo, put on the harness and tighten again so you don't mess with the leg straps) the harness isn't pulling up on the dildo at all.
Of course the SpareParts is probably a better choice if you can swing it. Not sure about the Aslan, but many harnesses can be worn by men as long as the dildo is over the penis. Sometimes there's a bit of rubbing, and I wouldn't be surprised if this happened with the Jaguar.
Can anyone with the Commando chime in on how well that works? Bare As You Dare?