I wonder how up to date the data is on the database, after the last patch. Some ceature values have moved.
For lvl 20 they are about 5500HAM, get that mountain dewback (lvl 20) and makes a nice medium mount. Also at lvl 20 are Ronto and last I checked the Greater Desert Womp Rat (but the rat might have gone up).
Greater Gulginaws are now lvl 21, as is the Desert Charger Gurrecks, my past favorite lvl 20s.