Possible Clues:

• Gold-coated mount
• Gold-and-white horse
• Friend o' the compiler's briefly seen with old horse
• Type of horse
• Cream-colored horse
• Pail kicked, moon shattered, that's some horse!
• White and gold horse
• Horse friend o' the compiler briefly owned at first
• Roy's Trigger, for one
• Roy Rogers' Trigger, e.g