The time sert is a good product but in this application i would try something from thread #7 above..less drilling and less chance of making things worse unless you have excellent access and the ability to drill straight...even if bike is placed on a modest lift it is still rather difficult to drill...

 

This link explains some of your options with pictures:
http://www.bigboyzcycles.com/showthread.php?t=85

 

I see the point about access under the bike, in the past I've used load straps on the bars going to trusses in the garage. Still have to lay on your back though to do much.

 

I also have a tranny drain plug that prb. was over tightened the last time by the previous owner or whoever did his work.I had changed all my fluids towards the middle of last summer and when I tightened the tranny plug it kept turning.I removed the plug and looked at it closely and it appeared something was on the threads.I wrapped teflon around the threads 3- 4 times and screwed it back in and tightened up nicely and I've never had a leak.Figured I'd leave well enough alone till next time.I read a bunch of threads on here to decide on what I needed to do next time.I went to the local bike shop and discussed possible cures and the one I went with was a tap and oversised plug that came packaged together.The guys at the shop have used this alot in the past and told me to be sure and put some grease on the tap,work it in a few threads,remove it,clean it off ,add more grease and continue doing this till I had the tap all the way in.I have this to do today so 'll see how well it works and keep my fingers crossed although I have thought about just leaving it alone and wrapping teflon again since I had NO leaks ,drips,seepage.I think all the fixes mentioned here and in older threads are all great,I just decided to go with the oversized plug...

 

The link does not show the option of getting a longer bolt than original.
Plenty of thread way up inside for the transmission drain.