we have the strkeback alarm fitted but it has to be done by them,most DIY alarms are for cars and not motorhomes where there can be air flow in the living area. thus triggering false alarms.
We have a Cobra security system (Thatcham cat 1) fitted. (Total cost c£280). This standard is a certificated system recognised by insurance companies and the work is carried out by a registered installer. It is an aid to reduced insurance premiums and peace of mind wherever you go.
Not the cheapest but as has been said before - can be armed with pets or people inside with no false alarms, and no pirs. Also, lifetime guarantee on control unit.
for a cheap option go for car alarm with infared censors.this will cover both doors and windows if beam broken alarm goes off also has motion sensor.must point out though its suprising how much power these alarms use,so keep check on battery statuse
thanks all for help ; am going with the van bitz strikeback, after spending over 20k for a van i think it would be foolish to cheat on keeping it safe.