Changing on the go

Does anyone else have issues with IBS and needs to change when out and about?   I have a diaper change bag with everything I need in it.  However; I don't want to bring it into a store or in public somewhere.   I have found changing in my vehicle more convienient because there really isn't a lot of room in public bathroom stalls; and the floor may not be clean to want to set your bag down on it.   Does anyone else have this issue?   I try to park away from where people are; but worry if someone should walk by; or if there is some security cam somewhere.  Anyone else have any advice?  Do you think anyone would care or be offended if they did see an adult changing their diaper in a vehicle; or if someone were helping them get changed?