Petrol tank Route Planning, Big petrol tanks Needed!

I have an ex-Police slimline petrol tank either off a Slimline Dominator or Atlas, I think the capacity was 4 gallons, perhaps being deeper than the 1960/61 Slimline tank pressings it was designed from, half the upper fluting is still n the tank. The radio mount square has been cut out and inside it has been oiled, but has a light rust, I was thinking of rubbing this down, wire wool and then perhaps treating the inner tank surface, though I have heard horror stories of some treatments sloughing off the inside of tanks the question is what to use?

I will have this tank modified for a single-seater Feather-bed, so it's going to be cut, lengthened, indented at the rear for the knees, internally baffled and will hopefully hold 5 gallons of juice.

The reason for this is that riding up to my parents in Lancashire or to Heysham Head for the TT's, I hate being ripped off by Motorway Service Stations or having to go into an unknown town and inadvertently being done for some Traffic Offence, like drifting into a poorly marked Bus lane or something, this has happened to me twice and cost me £70! Cash Cow syndrome!

100s and 100s of petrol stations no longer exist!

London for me is 80 miles, probably 65 to the Dartford Tunnel and I like to put as many miles between me & London heading North, before I stop for fuel and have my home-packed Spam sandwiches and a pint of God's finest, full-cream milk! I used to use the Blackwall Tunnel way and if not in a rush ride up through Epping Forest of just simply go past Leyton and pick up the M11.

Long ago I abandoned the M1 M6 route to the North-West England. I now go up the East side, A255, A299, M2, Watling Street/A2, M25N/M1/ M11, Dartford Crossing, A282,Junc 27 M11 S North-East London, keep right M11 N, Stanstead Airport/Harlow Cambridge, Huntington Road A14, A1,  Peterborough & the North, A1M, Doncaster and the North, Doncaster Bypass, A1, A1m, signs Wetherby/Manchester/Leeds, M62, (Trans-Pennine), M60 , M61  Preston/Lancaster, M6 and the Lake District if you are heading further up!

Sometimes I detour and call @ Howden to see Anna, but many years ago the Wife and I discovered Mexbourough near Doncastor and had a early breakfast @ Mexborough Castle in the grounds and infinitely better than the myriad of soulless Motorway Service Stations with Cost-a Lotta Coffee and such!

Riding solo the best time has been 5 hours by Motorcycle, 250 Honda! 340 ish miles in the early 80s, now this is no longer possible as speed restrictions and camera's have slowed us all down, so avoiding congestion it is now 6 to six and a half hours. The longest time has been 14 hours Motorway accident! I now set off between 3 and 4am, to avoid traffic and reflect on the fact this will be the 41st year I have been doing this particular journey by motorcycle or car, once restrictions are lifted.

John