I may be able to answer the security barrier question. Albion Street Car park in Huddersfield has a security barrier, pass activated, leading to a section for Council employees and certain others. You need a pass to enter, but to exit you need to activate a floor sensor, normally simply by driving a large metallic object like a car over a rectangle of tarmac in which the sensor is embedded.
The car park has several drain covers, perfectly portable, and heavy and ferrous enough to activate the exit sensors. SO. You park in front of the barrier, alight the vehicle, find one of the drain covers and place it on the corner of the sensor, neatly marked with a ribbon of bitumen. The barrier lifts, you get back in your car and drive in. You then take the drain cover from the sensor and put it back over the drain and Bob’s your mother’s live in lover.
Now I may be wrong, but I strongly suspect that a member of the travelling community may well be able to avail themselves of a suitable piece of ferrous metal to activate that type of sensor.