Fixed mountain climbing gear. Help please

I was thinking of using a spline crank and chainring for a tour of europe. The idea(if long winded)to change chain ring for accents and replace with larger ring for deccent. Would anyone know whether these components would be strong enough for this purpose? Or is this a totally rediculous idea?

Not sure what you mean TBH.

But if can get the chainline right. You can just use a compact road crankset (with say 44 and 34 tooth chainrings), and a flip/flop hub (with say 15 and 22 tooth sprockets). Giving you say:
44:15
34:22

or if you can afford it you can get a white industries double crankset and a surly double fixed sprocket. This might be easer to set up.

Should be doable somehow.