You are working with a basement here...
A rug would help... even some rubber matting. But I would be concerned about mold or if anything could get up under the rug.
If you have a way of getting some wood or metal you can make a drum riser. Having one of those you could either strap all gear to the riser, or bolt them into the riser.
The only bad thing about zip ties is removing them if you are going to play out. Since it is a temporary fix though it just might work.
You could attempt to put something heavy in front of the pedal, like a guitarist, which might work. Or if you have small children they could hold it in place for you.. lol
If you want something small to use I would get a piece of metal, shape it to how you want the bass drum pedals. Drill some holes for the spikes and invest in some high grade velcro... Not the cheap shoe brand but the hard plastic ones. Then you have a bass drum plate that will work on any bass drum you can go to. Your pedals would be portable this way. And if you got real funky with it you could add some rubber feet to the bottom. That little step there may help increase the resonance of the bass drum... Since the bass drum would only have the two legs of the bass drum and then the 3 or 4 rubber knobs on the underside of the plate touching the floor. Wow I like this little idea.