It's up to you I use the window frame sealant and gun it around all joints and you know what cr*p weather we get In UK and the result is fine, has to be done again in about 18moths well I do anyway.
Best method is NOT to cut the tube tip but build up in layers if necessary it does a neater job than having big thick worms coming out of a cut tube tips.
Alternative if you want the proper stuff and or none setting putty then try www.thetford.com.au and select for list of suppliers of thetford stockists I'm sure that's not all they would stock and it serves as good directory covering much of Australia.
UK camper off to our c/van next week on farm in Devon to see our daughter and family.
TIP
If you take off any of the ALLY strips to putty under them and the screw/s don't go back tight open the screw hole slightl and tap in a plastic rawl plug [screw wall plug] then refit you'll find the screw goes tight.
Been there done that on our previous caravan.
Nobby
April 2009