As a Instructor I can tell you SUT Small Unit Tactics will Whoop the older guys A$$ more then the younger guys, you live with a ruck on your back, and your recovery time from simple injury will effect you.
Also I personely would be watching you alot more closely. Mainly in my Experince the older guys from units like the guard will try to mule thier way threw this phase and be a helpful team member, but when it comes time to lead and execute things like issue a Op-Order, they are lost, lack of army Experince or troop leading ability Shows in the end, you can be in the greatest shape, be a #1 team player, but can you execute and lead troops ? most fail when they are put to the test.
Anyone can be a pack mule and hump a ruck and get selected. if thats your only trait then you will fail when you get to SUT, just a trend ive seen from the older folks that come threw this Phase. but maybe you are one of them freaks of nature we hear about
NOT LIKELY