Novice warning here...but here is my thinking...

Although I know nothing about pepper trees, anchoring a tree of this size can require considerably longer than 1 year. Starting from now, because wind-rock may already have seriously hindered the establishment of the trees, I would be looking to anchor it for a minimum of 3 years, maybe longer (with caveats).

How were the trees originally anchored - staked, guy-ropes? I generally go for an angled brace system, with at least 2 and sometimes 4 stakes at 45degrees to the trunk, reaching a third to a half of the way up the trunk, paying particular attention to prevailing winds. In my locale (East Anglia), the flat, ferociously exposed and windy sea-level surroundings require careful staking of most trees apart from maiden whips...but we usually fasten the tree-ties as low as possible to allow for flex and girth increase. In your case though, I would be tempted to screw guy-ropes directly into the trunk as you then have the option of adjusting the tension as the tree matures, allowing it to have increased movement - necessary for development. Sounds a bit drastic but given the possible bark damage by rubbing at even the softest tree ties, it is sometimes a matter of deciding which causes the minimum damage

I emphasise my novice experience here - a 20foot tree would be a considerable investment which repays due care and attention - am surprised more experienced arbourists have not yet replied to your post.

Desert trees and trees of that size need anchoring for considerably longer. Also, trees purchased in a box have a long recovery period before they start to grow normally. Hopefully you can slowly get them back to upright, and count on a couple years anchorage.

Thank you both for the information and advice. Sounds like I had better start looking for someone to stake my trees. Any suggestions on how to find someone that will do it right? The only thing I come up with is contacting the nursery I purchased them from. Thanks again for the advice.