i personally wouldnt advise the hilift being located on the inside of the vehicle. a hilift is a dangerous tool in the fact that is decently unpredictable, it weighs a lot and is not easily attached to anything. that said, being mounted on the outside of the vehicle exposes it to corrosion and dirt build up, which in turn also affects its reliability.
that said i have mine mounted on the outside, securely on 1/2" threaded studs. i only have it mounted for trips and i make sure it has fresh paint on it and is lubricated regularly.