This isn't a triggered ability (so you can't play the Glade and then tap it to pay for that cost), it's a cost that you'll have to pay alongside playing the land itself if you want it to enter
That said, custom proxy cards are generally not permitted in officially sanctioned Wizards of the Coast tournament play
While attached, this isn't a creature.) P/T Number 94 Language English Legal Formats Commander, Legacy, Vintage Not Legal Formats Alchemy, Brawl, Competitive Brawl, Historic, Modern, Pauper, Pioneer, Standard, Timeless Rulings (6/7/2024) The value of X is calculated only once, as Razorfield Ripper's triggered ability resolves
Unfortunately, theres no fix or workaround for this issue
Greedy Fang drawing two cards keeps your engine moving, but its Hungry Jaws that has truly caught players attention
Try to use Blockers to protect against smaller attacks of 5000 or 6000 power, while using Counter Events to protect rested Blockers, or against stronger attacks