The '64 has a similar vent layout as my Globetrotter '67 did. On the GT a Coleman unit was installed midships. I do not know if it had the roof reinforced. I recall seeing a video where someone was using 2X2 wood to fill the space between the inner and outer skins under the A/C on a '60's rig.
I added an A/C unit to the '72 Tradewind between the center and rear vents and did have to reinforce the roof with aluminum channel.
AirForums # 2806
WBCCI / VAC # 6411
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