The mastic we used was just normal white silicon bathroom sealant and I just used the usual type of sealant gun, so if you don't have enough room to use one I am not sure what I can suggest. I'll find out which parking sensors my other half put in and will put them on here.
Are they the ones labelled 52 litre? I use a Really Useful 48 litre box, which has room to spare for the grey waste drain hose. Perhaps your cassette is bigger. Or maybe you bought the 28 litre size.
Yes, we bought the 52 litre. The cassette fits in there with only a couple of cm spare on the length and a snug fit on the width. Hopefully, there will be no sloshing about.....
The parking sensors my OH put in are: https://www.amazon.co.uk/gp/aw/d/B07R5YPD1Q?psc=1&ref=ppx_pop_mob_b_asin_title
Tail bord elegal if no fog lite,unless you can see vh one,police nab many here,trailer also requires a brakeaway chain.
Interesting. I like the Really Useful box range and I think I have a couple of 48L ones (full of CDs and DVDs). I'll check that for size before buying another box
Two young lads doing the test, I held back and didn't mention that it was older than them. So sat in the plastic chair provided I tried to observe as well as I could. Very thorough they were too. Though I expect most of it was a history lesson to them. Low and hold it passed without having to hand over the £250 in cash 
