A cheap and cheerful way to mount wire antennas and verticals when portable is a cheap Squid Pole. These fibreglass poles are available in many sizes and styles from fishing stores all over the country.
One example antenna using the squid pole as a base is this simple multi band vertical from VK7JJ.
I plan to use my squid pole to mount the end fed vertical i am building
On a recent camping holiday I explored mounting options for a 7m pole I obtained form a recent 4wd/fishing expo event. These are cheap and light when away camping collapse down to a small size easy to pack away and carry.
The camper trailer we have came with a 3m aluminium pole/antenna for tv, (that we don’t use) but I had left this pole in the camper tool box, the squid pole I purchased was aimed at slipping into the tv pole mount bracket, but the plastic base cap was just a little to big for this mount, I spent some time trying to reduce its size with a Stanley knife, but gave up and instead used the 1st section of the aluminium pole as the main base support as can be seen in the below photos, this gives me an 8m+ tall pole that will be the basis for antenna experiments when away. Ill update this when I get the antenna built and start using the antenna in anger 😀