When looking for a mast also take into consideration how self supporting it
might or might not be.  At another qth I used a flag pole.  It didn't
telescope but it pibited down on a mount.  The only problem was I got greedy
and wanted to add 10 more feet.  Thankfully I was younger then.  24 feet
wasn't bad.  After adding another 10 feet of 2.5 inch heavy pipe it was a
bear to raise and lower.
Rich