Is there a way to send someone a stack of items? I considered using the Trade but I discovered I couldn't do more than 10 items that way.

you can send the items one by one or 10 at a time using trades or put them in your shop for a super high price so nobody else will buy them, and then you refund the person the sP from your shop till.

They seem to make it difficult to trade mass amounts to prevent abuses such as having multiple accounts and transferring items between those. SO indeed, no magic tool.