A little knowledge is a dangerous thing, the becm is under the driver seat, the EAS ecu is under the passenger seat.
If you want an honest answer FIX it don't BODGE it
Unlikely to be RL20 from what you describe, more likely to be the piston seal worn which means that the compressor has to work harder or you have a leak somewhere causing the compressor to again work harder, does the suspension drop overnight.
Have a look here and watch the...
Sorry Symon, like myself most people here own the P38s and it would seem that those with the newer ones only ask for advice not give it :(
All i would say is get someone who is familiar with them to check it out before purchase, it's no guarantee I know but better than nothing.
TBH it's more down to what the customer has requested, mines a HSE but it has full walnut dash and console, sat-nav, hk sound, memory seats, drop down video screen etc etc, very rare to find 2 the same.