Sorted! Had another go today and, with heat, got the hose carefully into place. With a bit of pressure it popped into place and it's pictured here at 34psi. Arch clearance has gone from one finger to whole width of hand at full pressure, with rear camper conversion and 85L LPG tank minus our camping luggage, which bodes well. Will do the other side tomorrow night then see how it drives. Thanks Rob!