Do you need to show proof of funds to visit Mexico for 5 months?

there no financial requirements fmm tourist permits, in fact can take quick trip down belize , 6 months.
time need financial records if applying fm3 , fm2s . first visa temporary residence other permanent residence.

wondering if book flights (uk-mex) leaving april , not returning until october have trouble @ customs since such long stay in mexico?
if request proof of fund how many peso should have in account?

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