Baggage to Lord Howe There is a 14kg per bag outward limit from Sydney and Brisbane, and you are allowed a carry on up 7kg, and you can book an extra 14kg bag.
The Extra 14kg bag may not travel on the same flight as you, but could arrive the next day and would be delivered to your accommodation on Lord Howe.
Return flights are not an issue because all the Qantas staff at Lord Howe are local residents and they let that sort of thing slip, they do not want to hassle their tourists.
The way I would get around the issue is to use one of those bags that splits in two, that way you could have 28kg of booked in luggage, which is up too 4 kites, your board and wet suit etc. I would carry the bag to the airport clipped together as one bag, when I get to the check in counter I split it into two.
Fit as much in your carry on bag, in an airline approved carry on backpack. They do not normally weight your carry on. The check in person will warn you that your extra bag might not come on the same flight, but normally does. The only time extra bags will not come on the same flight is if the flight is completely full, and at this time of the year the flights are not often full.
Book the extra 14kg bag online the price at the airport is double, I'm fairly sure it is only $30 online.
www.qantas.com/travel/airlines/prepaid-additional-baggage/global/enIf you need any other help let me know, you probably will not need big kites as the winds in winter tend to be 20-30 knots.
If you want to ship stuff prior, send it in a 5kg express post bag, which is shipped by air and get there quite quickly usually within 24-48 hrs from Brisbane, can take an extra day from Sydney for some reason. Use an Express Post bag not a box as it is cheaper.