The installer lifted the GXP 17-4 antenna to 110 ft and could not get it any higher. 
Partly because his gin pole was unstable. He arranged for a younger installer, who was waiting for a good weather on a weekend. All while the 40m element was grinding in the wind. 
After a few weeks waiting I wondered if there was any other option. I asked for opinion a prominent installer in the NE. Looking at the tower’s picture, he answered that everything with the setup is wrong and that he can fix it for $10-15k.
Beware of a guys who say everything is wrong and ask for a fortune! A month ago our garage door did not open. One installer said that everything was wrong and it would cost $6k for a new door. Another installer came, said the door was fine, fixed a few minor items, and installed a new opener for a fraction of the cost.
A friend of mine Waldek N4PL had a gin pole Rohn style with a 2 inch aluminum tube. I asked the towertalk group on groups.io if that pole would be sufficient for a 200 lb 40ft antenna, and the opinions were generally positive.. Ron WV4P suggested to simple lift the antenna from the top of the mast. Ron knows what he is doing.
With Waldek we decided to lift the antenna with 2 pulleys, one attached to the gin pole and another one to the top of the mast. Both cranked up with hand winches.
While I was cranking, N4PL kept the antenna short of obstructions. .
Cranking was hard since the rope (5/16 Dacron) would not wind evenly. It was necessary to ease one crank, putting all the weight on the other crank, to reposition the ropes a few times. Both the gin pole and the mast never showed any stress.
Once the antenna was up, Waldek attached the mast clamps. Not easy as tolerances in the clamps were miniscule and the beam had to be exactly vertical. To level the beam, I stood on the higher side of the beam. Great fun.
Close to dust, Waldek installed a temporary coax and oriented the antenna to the NE.
EVerythin g looks fine except that the 40m driven element is slightly bent from banging in the wind. 
Would the antenna be good despite banging in the wind? The SWR curves were OK:
Quick tests on the air showed that on 40m the antenna is about 3 db better to EU than my 2 el beam. On 20m, its is about 1 db worse than my stacked 3 el, meaning it is about 2 db better than the 3 el @ 100 feet. As expected.
So the ordeal to get the antenna up is over. Thanks to Waldek N4PL without whom the work would not be successful. For a long time he has been climbing towers and he has wealth of experience fixing things.