I had this same question several years ago, before we had this site or Roo as a resource; my thoughts about saving money on a firesuit were identical with respect to whether a tunnel would suffice, rules-wise, anyway. I'm not looking at a rulebook as I type this, but as I recall, the relevant wording, in General Regulations(?), as regards the -20 suit was "...or if the transmission is within the driver's compartment." Which my shorty 'Glide is, totally, at 32" out, even though it's on gas, not blown, and not all that fast. My footsies are alongside the transmission shield but behind the converter and the flexplate shield. It seemed to me that the gooder firesuit would be the bestest in the event of any transmission failure that might let hot ATF try to chicken-fry my chicken-legs. Same reasoning led to the purchase and use of fuel boots, even though not required.