I'm just going to evaluate the options you mention.
covering surfaces with blankets, duvets, or comforters
Not really a professional option and can actually cause bad results
covering surfaces with "acoustic geo textile" (literal translation from Portuguese, product here) with 5mm, 10mm or 20mm thickness
You can't really do much with 20mm ...
The reason that Waves store the files in a 'wir' format is to make them proprietary, thus preventing you from using them elsewhere. You would have to reverse-engineer the 'wir' file format, extract the impulse, then move the impulse to another system before you could use it. Probably not worth the hassle.