Got a call from a repeat car customer, wants his 37 foot RV done- just wash/wax. I average about $2-4 per linear foot for just exterior wash/wheels/windows. Never had to wax an exterior, looks like most people do $10-$18 per foot complete details. This won't need a wheel, just hand wax- is $7 per foot too cheap? I don't want to hurt this guys wallet if it will help me get two more easy waxes out of him this season. No interior, should take 4-5 hours tops, 7 x 37 = 250, still rape. help?