I haven't ever tried to iron pants (at least the leg parts) with the board inside the legs. I always press them flat from hemline up to the hip line so that there are creases front and back.
The last time I bought an ironing board, I bought the best one I could find. It adjusts from very low (iron sitting down) to way higher than I need it! How wonderful to get an ironing board up high enough for a change. It's 17" x 49". It's not mesh - it's got the diamond shaped holes punched in the top.
But, I replaced the cover with two layers of low-loft cotton batting and made a tight cover of two layers of cotton muslin. I never have any trouble with moisture in it - at least I don't think I do.
The huge OSB pressing board that I lay on top of the ironing board holds moisture in the batt and canvas cover, but not the ironing board, itself.
Get the sturdiest ironing board that you can - you spend a lot of time pressing and it's so much more pleasant when you aren't fighting one of those tippy little too-small boards. :)
And a sturdy ironing board will support a big plywood pressing surface so that you can press whole widths of fabric at once. :D