Binary datatype limitation

I need binary field 1020 bytes length. It is possible increase maximum size of binary type from 255 to 1020 or 65536? I use a binary string as fixed array and change elements by INSERT(str,pos,len,newstr) function. BINARY fields filled with 0x00 (the zero byte) by default, and this is what I need. But its limited by 255 bytes only. I tried to use varbinary, that support lengh up to 65536, with setting DEFAULT to ‘\ 0 \ 0 \ 0 … \ 0’, but in my company use Naviсat, which clears default value on any table change.