I think this also was one of the bigest improvements I have made to my 13ft Boler.
welding the jacks to the back cut my set up time from about half an hour to about 15 minutes.
This season I plan to add 2 more jacks to the front because I am not to sure that the original (1980) tounge jack will hold up its end of the bargain so to speak.
The only thing I think I am goin to do is place the jacks alittle further under by trailer where the support will be more evened out from the back jacks to the wheels to the front jacks and just use the tounge jack to hold up the gas bottle and battery box.
Gerry