Troubles with RNA extraction from mouse skin.

I'm trying to obtain RNA from mouse skin but the results have not been satisfatory. I observed chemical contamination and also very low amounts of RNA (1-5ng). I'm working with a murine model who has collagen overproduction and usually freeze the samples directly in -80°C in RNAlater.

Qiagen support told me that the RLT buffer can crystallize and that I should use a water bath at 37°C after this specific step to dissolve the crystals (this is not recommended in the kit). Do you think this is possible even working at room temperature? Any other recommendations ?