You can buy plastic snap-in caps for standard sized box tubing - kinda like what you see use on gym benches and weight lifting equipment. That's what I'd use - siliconed in place.
2000 SVT Turbo 295hp/269ftlb@12psi
#1 for Bendix Brakes Kits!
Knuckles rebuilt w/new bearings $55
AUSSIE ENDLINKS $70
Gutted pre-cats $80/set
A lack of planning on your part does not constitute an emergency on mine!