You are employed as a contractor so that your employer can get out of sick and holiday pay, workers comensation, superannuation etc etc. It's a scam that has gone on for years and continues to do so because pilots keep falling for it.
Working as a contractor is not an excuse to accept less. Your contract hourly rate should take into account the above entitlements.
If you have signed some sort of contractual arrangment you also might want to have a close look at your liability should you bend or break an aircraft owned by your client. Contractors usually do not enjoy the same protection as employees when it comes to damaging equpment they don't own.