The carrying of waterproofs is not really a big deal compared to the problem thar ROs will have with number sequencing for pre-entered races when quite a few don't show.
the extra kit is more bureaucracy but easily managed. we have a long way to go till we get to triathlon rules where one competitor at helvellyn was disqualified for having no lights on his bike on a mild and clear Sunday morning - the rule was they had to be carried even though no one used them.

can you use pins or sticky pads direct on he chest

Always running just never at speed