Assuming that the general appearance is OK, you could take some 0000 steel wool, and solvent (lay mineral spirits) and rub the rusted areas to remove the loose rust. Care needs to be taken not to rub on the paint and thus change the sheen. With or without the steel wool, you could then apply a coat of old fashioned past wax, let dry for a bit, and polish with a soft cloth. The rusted areas will now have a bit of shine, but be sealed from further rusting.

Another possible, non damaging, preserving thing would be to carefully rinse the rusting areas with distilled water, and dry immediately (say with careful hair dryer or put in sun for a few hours), then wax. The water rinse will remove Chloride ions on the surface which do much increase the rate of rusting. This is especially effective in areas with damp and exposure to sea water. Note that areas within a few hundred miles of the sea have lots of salt in the air.

By the way the application of a source of chloride ions (Fe2Cl3),rusting in a damp area, removal of most of the loose rust by brushing with a wire brush (carding), repeating as required then rinsing with distilled water, followed by waxing is the old "browning" finish used on firearms in the good ole' days.