Two trains of thought.
First, my own experience, second , thoughts on what you have said.
I am over 60, and wear “XL” britches.
A couple of months ago I went to an “A” show (Warrenton Pony) and competed in a division (Connemara Halfbreds)where the other 7 competiors were young enogh to be my children or, in most cases, grandchildren, and all MUCH thinner than me.
I was really pleased with how Belle went, but she is NOT a hunter by any means (eventer and jumper), and we got a 5th and 2 6ths.
It never occured to me that our low placing was due to my age and weight. It was becuase she has more knee action, and more energy, than the ideal hunter. I primarily went to support the Connemara breed, and the show, not to win a blue ribon, though I woukd of course be thrilled if I did.
Also, one day division, no stabling, no trainer fees, total well under $300.
Your case-
Forget about the age and the weight.
But if winning a bkue ribbon is important to you, I would wait until you can do “the whole division”. In fact, I’d wai until you are almpost ready to do the next level.
After all, in classes you DO enter, you will be competing against riders who ARE doing “the whole division”.
Bottom line- if you are (internally) going to blame “NOT winning” on your age and weight, I would not recommend showing at all.
I have had classes where I sucked and got a blue ribbon.
But I have had many more classes where I thought I did great, and didn’t get a ribbon at all.
It is not about “me”, my weight, or my age. It is much more about how well the OTHERS do.