To me, it seems you're doing very well with the antenna 20 ft AGL. Want to get more, raise it to
100 ft,
Well just under. Structures over 100 ft need FAA 'clearance' and registration with the FCC.
But doesn't look to be adding any networks you already get, Just the local news from another area.
LP - in my experience you're limited to around 30 miles
Stations more than 75 miles, you need height (may also be beneficial for LP stations)
Also co-channel and adjacent, and their relative directions, has to be included in determining if you have a chance of getting them.
Whoops, looks like you want an antenna suggestion. - - - me bad
Do you require the VHF Low channels? You'd need one including that band VHF Lo/Hi & UHF.
Winegard HD8200U Channel Master CM3020 or similar.
If not, Just VHF Hi & UHF Winegard HD8200U or HD7698P Antennacraft HBU 44 or 55
If just UHF, just about any of the 4 bay bowtie's should do.