1) Carrying a BB cream must be on your priority list which can be a replacement for your oversized foundation bottles. Carrying eyeliner while travelling can also be a good option as it can also hide the tiredness in your eyes. Apart from that there should be some basic things in your travel beauty kit like some lustrous lipsticks, mascara, and face cleanser.
2) There are few products that can be used to compensate for the missing products. For example you can use lipstick as a blush on your face, kajal can be used as eyeliner and for contouring you can also use eyeshadow.
Going on a beach where the weather is all sunny and bright requires proper cleansing and moisturising of the face along with the application of a proper BB cream which also compensates for the foundation. It will give a good finish with the swipe of a bronzer and then using the highlighter towards the end along with the application a bright shade of lipstick.
Mountains and hills are refreshingly cool places, where one can go for bright orange and pastel colours paired with grey or black eye shadows. Also applying purple or pastel coloured lipstick will give a good finish to the look.